CDK4 and cancer: In lung cancers, CDK2 levels were over-expressed in more than 90% (Kawana et al. 1998), and CDK4/6 in more than 23% of the patient samples (Wikman et al. 2005; Weir et al. 2007) Therefore, a CDK 2/4/6 triple inhibitor will likely be more effective than CDK4/6 dual inhibitor in these cancers.