CDKN1B and cancer: Each of these mutations occurred in genes with demonstrated pathogenic roles in cancer and included activating mutations in ESR1 (D538G), ERBB2 (V777L), AKT1 (D323H), and PIK3CA (E542K), as well as inactivating mutations in RB1 (N258 frameshift), TP53 (V173L), and CDKN1B (S2 nonsense) [8, 25–28].