D-threo-PPMP is a glucosylceramide (GlyCer) synthetase inhibitor.1,2It is the active enanantiomer and enzymatic inhibitory component of the racemic DL-threo-PPMP . In MDCK kidney epithelial cells, D-threo-PPMP induces a 70% reduction in cell growthin vitroat 20 μM and significantly inhibits DNA synthesis at 3 μM.3