Overview of using the Paired-SSN to construct the personalized state transition network. First, select all of the normal data as the reference data, and construct the tumor network and normal network based on the reference data with the SSN method [86]. Then, construct the single sample network with SSN, in which edges are those existing in both the gene–gene interaction network and the co-expression network for each sample. Finally, construct the personalized state transition network in which the edge between gene i and gene j exists if the P-value of the edge is less than (greater than) 0.05 in the tumor network, but greater than (less than) 0.05 in the normal network.