TI - Effect of prolactin on [Ca2+] i levels and PHOSphorylation of Ca2+ -dependent PKC isoforms in normal female cholangiocytes . AB - Prolactin induced a sustained increase in [Ca2+] i levels in normal female cholangiocytes compared with cholangiocytes treated with 0.2% BSA ( Figure 5 , top panel ) . A calcium tracing , which is the average of three independent measurements , is shown in Figure 5 ( lower panel ) . As the tracing shows there is no change in fluorescence during the basal measurement period that demonstrates that the cells do not leak as influx of extracellular calcium would alter fluorescence ( Figure 5 , lower panel ) . Cholangiocyte responsiveness to the Ca2+ ionophore , ionomycin [31] , is shown in Figure 5 ( lower panel ) . When purified female cholangiocytes were treated with prolactin , there was an increase in the phosphorylaTION of PKCbeta-I and a decrease in PKCalpha phosphorylaTION ( Figure 6 ) ; no significant changes in the PHOSphorylation of PKCbeta-II and PKCgamma were observed in normal female cholangiocytes treated with prolactin ( Figure 6 ) .