Inositol phosphate (InsP) accumulation in COS-7 cells transiently transfected with wild-type and mutant OXTRs. Transfected cells prelabeled with myo-[3H]inositol were treated with buffer alone or with 100 nM oxytocin. After one hour of incubation, inositol phosphate accumulation was measured as described in Methods. (A) Oxytocin-stimulated InsP accumulation. Results are presented as fold change compared with unstimulated (basal) InsP levels. (B) Comparison of basal levels of InsP accumulation in transfected cells. Results are presented as the ratio to the unstimulated (basal) InsP levels in cells expressing wild-type receptor. Data are mean ± SEM of multiple experiments performed in duplicate.