CDK6 and acute lymphoblastic leukemia: The Cereblon-recruiting PROTAC YX-2-107 was identified as a potent inhibitor of in vitro CDK4 or CDK6 kinase activity (IC50 = 0.69 and 4.4 nM, respectively) comparable to Palbociclib (IC50 = 9.5 nM) as well as a selective CDK6 degrader in Ph+ BV173 ALL cells with a degradation constant, DC50, of ~4 nM, based on densitometric analysis of CDK6 band intensities over a range of YX-2-107 concentrations [126].