ESR1 and invasive ductal breast carcinoma: Notably, when we stratified the cell lines based on histological type (invasive ductal carcinoma—IDC versus not-IDC)21,22, we observed that the reduction in ERα levels caused by esiRNA treatment against the 11 kinases was significantly overall higher in IDC cells (MCF-7, ZR-75-1, T47D-1, BT-474) than in not-IDC cells (HCC1428, EFM192C, and MDA-MD-361) (Fig. 2d and Supplementary Table S4).