Not surprisingly, similarity among different cancer types was identified in only 6 out of 23 clusters, including E3 (IRS2, KRT6A), E5 (CD24, STMN1), E8 (GKN1, MUC5AC), E9 (PHGR1, TFF3), E10 (TFF3, TPO) and E13 (VTN and ITIH5) (Supplementary Fig. S2c, d). Here, IRS2 is linked to cancer.