<prompt> The following is not a cell cycle inhibitorP21P27P16INK4aCyclin D-CDK4 complex  <response>: Checkpoints Cyclin CDK G1-S Cyclin D CDK 46 Cyclin E CDK 2 G2-M Cyclin A CDK 21 Cyclin B CDK 1 Family Checkpoints Proteins Functions CIPKIP CDKN1 G1-S G2-M p21 p27 p57 p21 induced by p53 p27 responds to TGF-ss INK4ARF CDKN2 G1-S p15 p16 p18 p19 p16INK4a binds to cyclin DCDK4 promotes inhibitory effects of RB p14ARF increased p53 levels by inhibiting MDM2 