Phosphoinositide-specific phospholipase C (PLC) plays a significant role in transmembrane signaling. In response to extracellular stimuli, such as hormones, growth factors and neurotransmitters, PLC hydrolyzes phosphatidylinositol 4,5-biphosphate (PIP2) to generate two secondary messengers: inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG) (1). At least four families of PLCs: PLC beta, PLC gamma, PLC delta and PLC epsilon, have been identified. The PLC beta subfamily includes four members, PLC beta1-4. All four members of the subfamily are activated by alpha- or beta-gamma-subunits of the heterotrimeric G-proteins (2,3).Phosphorylation is one of the key mechanisms that regulates the activity of PLC. Phosphorylation of serine 1105 by PKA or PKC inhibits PLC beta3 activity (4,5). Serine 537 of PLC beta3 is phosphorylated by CaMKII and this phosphorylation may contribute to the basal activity of PLC beta3. PLC gamma is activated by both receptor and nonreceptor tyrosine kinases (6). PLC gamma forms a complex with EGF and PDGF receptors, which leads to the phosphorylation of PLC gamma1 on tyrosine residues 771, 783 and 1245 (7). Phosphorylation by Syk at tyrosine 783 activates the enzymatic activity of PLC gamma1 (8). PLC gamma2 is engaged in antigen-dependent signaling in B cell and collagen-dependent signaling in platelets. Phosphorylation by Btk or Lck at tyrosines 753, 759, 1197 and 1217 is correlated with PLC gamma2 activity (9,10).