Levels of active PKCβII correlate with membrane-associated Btk and with pY⁷⁵⁹-phosphorylated PLCγ2. (A) Plot of membrane-associated Btk against membrane-associated (active) PKCβII in CLL cells (n = 12). The percentage membrane association of Btk in CLL cells was determined from membrane and cytosolic subcellular fractions, as described for PKCβII. (B) Plot of pY⁷⁵⁹-PLCγ2 against membrane-associated (active) PKCβII in CLL cells (n = 12). The degree of pY⁷⁵⁹-PLCγ2 was determined in Western blot analysis of whole cell lysates, taking the ratio of the densities of the bands recognized by antibodies specific for nonphosphorylated PLCγ2 and for pY⁷⁵⁹-PLCγ2. Results are reported in arbitrary units.