SLC15A1 and malignant colon neoplasm: 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).