Once again, the combined drug treatment resulted in induced expression of the SLC15A1/PEPT1 transporter; however, decitabine alone did not influence the expression of this transporter in the Caco-2 colon cancer cell line, and this reinforces the notion that its epigenetic regulation is primarily driven by HDAC1 (see below for mechanistic studies). This evidence concerns the gene HDAC1 and malignant colon neoplasm.