ERBB2 and breast cancer: In breast cancer, FGFR4 was overexpressed in 33% of HER2-enriched tumors (PAM50 classified, n = 58) [48], and significantly associated with poorer overall survival compared with the non-overexpressing group (Fig. S1B; P = 0.044; FGFR4 overexpression in 4% of all breast cancers; n = 825 [4]).