a, Control cells treated with fluorescent NBD–PtdlnsP3 (30 μM)–histone (10 μM) for 5 min. b, Cells treated with NBD–PtdlnsP3 (30 μM) without histone carrier. c, Cells pretreated with LY 294002 (200 μM) for 20 min and then exposed to NBD–PtdlnsP3 (30 μM)–histone (10 μM). d, Cells were pretreated with toxB and then exposed to NBD–PtdlnsP3 (30 μM)–histone (10 μM). a–d, Nomarski images, a′–d′, immunofluorescence images.