CDKN2A and diabetic kidney disease: To understand the role of p16 in DKD, first, we found that the expression of p16 was increased in kidneys from DM mice compared with age-matched wild-type mice, as analyzed with Western blot (Fig. 1A), quantitative reverse-transcription PCR (qRT-PCR) (Fig. 1B) and immunohistochemistry staining (Fig. 1C).