Immunoblots of PLCβ isoforms in wild-type and PLCβ2/β3-null platelets. Total cell lysates containing human or murine platelets were fractionated by gel electrophoresis and immunoblotted with PLCβ isoform-specific polyclonal antibodies. (A) Murine platelets have relatively less PLCβ2 and relatively more PLCβ1. (B) Murine platelets lacking PLCβ2 and PLCβ3 did not have a compensatory increase in PLCβ1 or PLCβ4.