We examined UCHL1 expression in normal mammary epithelial cells (MCF-10A) and some subtypes of BC cells (ER+ HER2−: MCF-7 and T47D; HER2+: SK-BR-3 and BT474; ER− HER2−: SUM-1315 and MDA-MB-231). This evidence concerns the gene UCHL1 and breast cancer.