Effects of PKC and phosphatase inhibitors on Na/Mg exchanger activity. Erythrocytes were incubated with and without the following 100 nM: chelerythrine (CH), calphostin C (CC), okadaic acid (OK), and calyculin A (CA), and Na/Mg exchanger was measured as described in “Patients, materials, and methods.” (A) Normal erythrocytes. (B) Sickle erythrocytes. The error bars represent the mean ± SE of 5 experiments in triplicate determinations.