p21 is suppressed by SNHG20 in colorectal cancer, where it stimulates cyclin A1, leading to intensification of proliferation and migration (196) P21 is classically considered as a tumor suppressor, being involved in the downstream pathway of the p53 cell cycle arrest and in the assembly of cyclin D-CDK4/CDK6. This evidence concerns the gene TP53 and colorectal cancer.