The PMA-induced calcium influx is inhibited by ω-agatoxin-TK, a P-type calcium channel blocker.

Flow cytometry tracings are shown for Fluo-3/am–loaded RBC cell suspensions pretreated with 1 μM ω-agatoxin-TK and then stimulated with 3 μM PMA. Pretreatment of Fluo-3/am–loaded RBCs with PBS (the agatoxin-TK solvent) showed no inhibition of calcium uptake. Tracings representative of 4 different donors are shown.