CDK9 and diffuse large B-cell lymphoma: When cyclin-dependent kinase 9 (CDK9) inhibitors were applied to down-regulate both BFL-1 and MCL-1, an induction of apoptosis in BH3-mimetic–resistant lymphoma cells was observed, and regression of BFL-1+ DLBCL was achieved in patient-derived xenograft (PDX) models [56].