PKC isozyme levels and phosphorylation of membrane skeleton proteins in 4.2–/– RBCs. (a) Western blots of PKC isozymes in RBCs. Each lane contains equivalent amounts of cytosolic protein from 4.2-null (–/–) and normal (+/+) RBCs. Left, PKC-α; middle, PKC-βI; right, PKC-βII. (b) Basal and PMA-stimulated phosphorylation of RBC membrane skeleton proteins in normal and protein 4.2–deficient RBCs. Sp/Ank, spectrin and ankyrin. Add, adducin. 4.1, protein 4.1. 4.9, protein 4.9.