Ectopic expression of p16 protein in JKB cells. Total lysates obtained from JKB cells transfected with control vector (JKB control), wild-type p16 gene (JKB p16WT), or mutated p16 gene (E119G)(JKB p16MT) were immunoprecipitated with anti-p16 MoAb followed by Western immunoblotting with the same MoAb. IP and WB with anti-CDK4 or anti-CDK6 polyclonal Abs served as controls. Expression of p16 protein was determined after 7 days (A) and 2 months (B) of puromycin selection.