We investigated the mRNA expression of pro-apoptotic effectors (BAX, BAK, BOK), BH3-only proteins previously involved in MTA-induced cell death (BID, BIM, PUMA, NOXA) and anti-apoptotic BCL2 family members (MCL1, BCL2, BCLX, BCLW, BCLB) within fresh-frozen tissue samples of different molecular subtypes from 92 patients with primary BC. The gene discussed is BOK; the disease is breast cancer.