CBS and colonic neoplasm: In conclusion, the current study identified and characterized the isopropyl ester derivative of AOAA, YD0251, as a novel CBS inhibitor molecule (AOAA prodrug) with significant antiproliferative efficacy in cell culture models of colon cancer (including efficacy in multi-drug resistant variants of human colon cancer cell lines), and with significant antitumor effects in tumor-bearing mice models (Figure 11).