ESR1 and breast cancer: The sensitivity of all the BC cell lines to all the CGs profiled in the database (i.e., resibufogenin (Resi), K-strophanthin (K-Stro), digitoxin (Digi), and digoxigenin (Digoxig), lanatoside-C (Lana), peruvoside (Peru), digoxin (Digo) and ouabain (OU)) was studied by stratifying the results according to the ERα expression [14,15].