PIK3CA and breast carcinoma: Interestingly, a recent RNA-seq analysis in BT20 breast cancer cells (which carry an activating PIK3CA mutation) identified FILIP1L as the most upregulated gene following treatment with vitamin C, and further implicated KDM5-mediated H3K4 demethylation in the mechanism of FILIP1L upregulation [64] suggesting that in addition to DNA methylation, histone H3K4 methylation has a role in the regulation of FILIP1L expression.