We studied the transcriptional regulation of human GM3 synthase (hST3Gal V) during monocytic differentiation of HL-60 cells induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). Northern blot and reverse transcription polymerase chain reaction indicated that the induction of hST3Gal V by TPA is regulated at the transcriptional level. To elucidate the mechanism underlying the regulation of hST3Gal V gene expression during the differentiation of HL-60 cells induced by TPA, we characterized the promoter region of the hST3Gal V gene. Functional analysis of the 5'-flanking region of the hST3Gal V gene by the transient expression method showed that the -177 to -83 region, which contains a cAMP responsive element binding protein (CREB) binding site at -143, functions as the TPA-inducible promoter in HL-60 cells. In addition, gel shift assays and site-directed mutagenesis indicated that the CREB binding site at -143 is crucial for the TPA-induced expression of the hST3Gal V in HL-60 cells.