IGFBP6 and cancer: The 835 prognosis classifier contained many cancer genes, such as Trp53, Myc, Kit, RB1, EGFR, CCND1, and CCND2 [36], and several genes involved in growth factor signaling, including TGFβ (TGFBI, TGFb1, TGFB2, TGFB3), IGF (IGF1, IGF2, IGFBP6), PDGF (PDGFB, PDGFRA), EGF (EGFR) and VEGF (VEGFc, VEGFA), all of which are involved in both mammary gland development and carcinogenesis (Table 1).