Figure 2. The thyroid cancer pathway in KEGG (ID: hsa05216).

The top rectangle marked by C1 shows that REDPTC and TRK have an indirect effect on the activation of Ras. Ras then activates BRAF, and BRAF phosphorylates MEK which in turn phosphorylates ERK. The result of this path is proliferation survival. This pathway has five connected components (C1–C5). Among them, C2 is actually a subset of C1, and the others are fully disconnected, i.e., there is no significant interaction between any pair of the components.