These software tools because these tools only focus on the statistical analysis of network topology without considering the diverse and complex network structures of regulatory motifs. Recently, several computational modeling studies have revealed the minimal network structure of regulatory motifs for the representative bio-signaling such as oscillation, adaptation, and bistability and suggested them as the core regulatory mechanisms that control the cellular function of the biological system [3,12,13]. These regulatory motifs are all 2- and 3-node network topologies with signed directed edges, and they are parametrically robust in exhibiting dynamic behaviors. These studies assumes that the network structures of regulatory motifs often include various sizes of cascades composed of multiple molecules and their regulatory interactions with activation or inhibition and these cascades can be reduced into single regulatory interactions if we consider the effect of the cascade on the regulatory property. Thus, in order to detect the regulatory motifs, it is necessary to compress the signaling network into smaller network that retain the original network’s dynamic properties and analyze the compressed network using the compressed forms of regulatory motifs composed of 2- or 3-nodes. Currently, there are several computational methods that involve simplifying complex networks [14,15,16]. These methods can be largely classified into two categories by focusing on network 18204824 topological or dynamical properties. The methods focusing onRMOD: Regulatory Motif Detection Toolnetwork topological properties include coarse graining and Title Loaded From File filtering approach, which strive to preserve static topological properties, such as the small-world property, scale-freeness, fractality, or modularity [14,15]. The other method focusing on network dynamic Title Loaded From File property is the kernel identification algorithm, which only provides the unique way to transform the original network into smaller network while preserving the network dynamic properties [16]. Since the kernel identification algorithm can be effectively applicable to the signaling network, it is possible to identify regulatory motifs and their regulatory properties using the compressed form of regulatory motifs after compressing the signaling network. However, it is insufficient to detect regulatory motifs based on the network compression algorithm. Because the signaling network can have more than thousands of nodes and their regulatory interactions, it requires efficient subgraph search algorithm capable of detecting all occurrences of subgraphs matched with the compressed forms of regulatory motifs on large-scale signaling networks. Among the several subgraph search algorithms considering subgraph isomorphism [17], the VF2 algorithm is known as the most efficient method showing the less CPU times and memory consumption [18]. This algorithm extends a partial matching using a set of feasibility rules to decide whether to extend or backtrack and employs a depth-first search strategy in a recursive fashion. However, this algorithm is not effectively applicable to large-scale signaling networks because the depthfirst search strategy causes exponential increases in search space as the size of network increases. Here, we describe a RMOD, a web-based system for the analysis of regulatory motifs in the signaling network with a novel computational approach for identifying regulatory motifs and their properties. Considering that regu.These software tools because these tools only focus on the statistical analysis of network topology without considering the diverse and complex network structures of regulatory motifs. Recently, several computational modeling studies have revealed the minimal network structure of regulatory motifs for the representative bio-signaling such as oscillation, adaptation, and bistability and suggested them as the core regulatory mechanisms that control the cellular function of the biological system [3,12,13]. These regulatory motifs are all 2- and 3-node network topologies with signed directed edges, and they are parametrically robust in exhibiting dynamic behaviors. These studies assumes that the network structures of regulatory motifs often include various sizes of cascades composed of multiple molecules and their regulatory interactions with activation or inhibition and these cascades can be reduced into single regulatory interactions if we consider the effect of the cascade on the regulatory property. Thus, in order to detect the regulatory motifs, it is necessary to compress the signaling network into smaller network that retain the original network’s dynamic properties and analyze the compressed network using the compressed forms of regulatory motifs composed of 2- or 3-nodes. Currently, there are several computational methods that involve simplifying complex networks [14,15,16]. These methods can be largely classified into two categories by focusing on network 18204824 topological or dynamical properties. The methods focusing onRMOD: Regulatory Motif Detection Toolnetwork topological properties include coarse graining and filtering approach, which strive to preserve static topological properties, such as the small-world property, scale-freeness, fractality, or modularity [14,15]. The other method focusing on network dynamic property is the kernel identification algorithm, which only provides the unique way to transform the original network into smaller network while preserving the network dynamic properties [16]. Since the kernel identification algorithm can be effectively applicable to the signaling network, it is possible to identify regulatory motifs and their regulatory properties using the compressed form of regulatory motifs after compressing the signaling network. However, it is insufficient to detect regulatory motifs based on the network compression algorithm. Because the signaling network can have more than thousands of nodes and their regulatory interactions, it requires efficient subgraph search algorithm capable of detecting all occurrences of subgraphs matched with the compressed forms of regulatory motifs on large-scale signaling networks. Among the several subgraph search algorithms considering subgraph isomorphism [17], the VF2 algorithm is known as the most efficient method showing the less CPU times and memory consumption [18]. This algorithm extends a partial matching using a set of feasibility rules to decide whether to extend or backtrack and employs a depth-first search strategy in a recursive fashion. However, this algorithm is not effectively applicable to large-scale signaling networks because the depthfirst search strategy causes exponential increases in search space as the size of network increases. Here, we describe a RMOD, a web-based system for the analysis of regulatory motifs in the signaling network with a novel computational approach for identifying regulatory motifs and their properties. Considering that regu.