Ptd(S)Ins-(3,4)-P2 (1,2-dipalmitoyl) is an analog of naturally occurring PtdIns-(3,4)-P2 that contains sulfur rather than oxygen at the sn-3 position of the glycerol backbone. Potential hydrolysis by PLC would yield a free thiol which could then react with chromogenic reagents such as DTNB (Ellman's reagent). There are no published reports on the biological activity of Ptd(S)Ins-P2(1,2-dipalmitoyl) or its use as a chromogenic substrate for PLC.