ESR1 and breast cancer: The second truncating mutant, namely, p27-E171* (chr12:g.12871794G>T, c.511G>T), was found in two patients with ER+ luminal breast cancer [73,74], in a subject with large intestine adenocarcinoma [75], and in patients diagnosed with sporadic SI-NET [76] or bladder (invasive urothelial) cancers (COSMIC ID: COSM3688044; ICGC ID: MU138318).