The treatment of mantle cell lymphoma cells with two different BET-PROTACs (ARV-771 and ARV-825), targeting BRD4 or BRD2/3/4, respectively, showed more potent apoptotic effect compared to iBET OTX015 (MK-8628), an iBET that selectively blocks BRD2/3/4. The gene discussed is BRD2; the disease is mantle cell lymphoma.