CDKN1B and cancer: Due to the influence of nonsynonymous SNPs on the amino acid sequence of protein, the role of a common SNP at codon 109 that encodes a nonsynonymous amino acid change of CDKN1B in the pathogenesis of human cancer has received widespread attention.19–23 Nevertheless, these genetic association studies produced highly controversial findings, failing to facilitate a full understanding of the mechanisms that underlie cancer.