Expression of CDKN1A/p21 in pan and breast cancer datasets. (a) CDKN1A gene expression levels in pan cancer dataset [55], including 15,648 normal, 40,442 tumour, and 848 metastatic samples; significant differences according to Mann–Whitney U tests are marked in red with an asterisk. (b) CDKN1A/p21 alteration frequency detected including all alterations, mutations, amplification, and loss. (c) CDKN1A gene expression analysis, RNA-Seq; normal, n = 403, tumour, n = 1097, and metastatic, n = 7 (TCGA Project “Breast Invasive Carcinoma” analysed using TNMplot), Kruskal–Wallis test T vs. N 1.9 × 10−51, N vs. M 8.86 × 10−3.