5-Azacytidine is a cytidine analog compound that functions as an inhibitor of DNA methyltransferase (DNMT) Its mechanism involves incorporation into cellular DNA/RNA followed by covalent binding to DNMT through the formation of a bond between the C6 position of 5-Azacytidine and the thiol group of cysteine residues in DNMT enzymes leading to reduced DNMT activity and subsequent DNA demethylation In cellular studies involving multiple myeloma (MM) 5-Azacytidine exhibits cytotoxicity against MM-derived cell lines (MM 1S MM 1R RPMI-8266 RPMI-LR5 RPMI-Dox40) with reported IC50 values of approximately 1 5 mol/L 0 7 mol/L 1 1 mol/L 2 5 mol/L and 3 2 mol/L respectively as well as patient-derived MM cells (IC50 1 5 mol/L) This compound is widely used in cancer research to investigate epigenetic regulation mechanisms and DNA methylation pathways