PKCβII is active in CLL cells. Subcellular fractions from CLL, HCL, and CD19-purified normal B cells were isolated using ultracentrifugation. (A) Western blot analysis of the distribution of PKCβII between membrane, designated M, and cytosol, designated C, fractions in the malignant cells from representative CLL patients. (B) Quantitative representation of membrane-association of PKCβII in CLL cells (n = 25), HCL cells (n = 5), and normal B cells (n = 3). Results are presented as the ratio of the band density of PKCβII in the membrane fraction over the combined densities within the membrane and cytosolic fractions. Tests for statistical significance were performed using the Mann-Whitney U test. (C) Correlation between PKCβII membrane association in CLL cells with an in vitro kinase assay of enzyme activity in crude preparations of total cellular PKC.