INK4 expression during terminal erythroid differentiation.

(A) Total RNA was isolated from HCD57, FVA, or MEL erythroblasts. Gel electrophoresis was performed, and ethidium bromide–stained rRNA was photographed as a control for loading. Northern blot analysis was performed using radiolabeled cDNA probes to p16, p19, p18, and p15. (B) Total cellular protein was isolated from FVA erythroblasts cultured for 0, 6, 14, 20, 26, 37, 42, or 48 hours with EPO (lanes 1-8). Proteins were electrophoretically separated in 12% polyacrylamide gels and probed with antibodies to p19. gp55 protein expression is shown as a control for protein loading.