CDK6 and breast cancer: However, the PI3K/AKT signaling pathway was highly expressed in clinical BC samples by qPCR and IF staining assays (Fig. 4E–G; Supplementary Fig. 1K, L), and H3K18la was positively correlated with PI3K, AKT, CDK4 and CDK6 by Spearman’s analysis, respectively (Fig. 4H–J).