SHC1 and breast cancer: Additionally, it is worth noting that p66Shc levels, as well as other isoforms belonging to the ShcA protein family in the investigated MDA-MB-231 breast cancer cell line (wild type) and the other breast cancer cell line MCF-7, showed their decreased levels in comparison to the control line (MCF-10A—non-tumorigenic normal mammary epithelial cells) (see Supplementary Figure S1).