Figure 1. Cyclin E protein regulation during terminal erythroid maturation is phosphorylation dependent.

(A) Left - bone marrow cells were sorted based upon expression of CD71 and Ter119 and subpopulations collected for immunoblot and RNA analyses as shown in subsequent panels. Right - lysates were prepared from the indicated bone marrow erythroid cells pooled from two wild-type mice and immunoblotted as shown. HDAC2 expression is used as a nuclear protein control for comparing the relative abundance of the cyclin E nucleoprotein in the different erythroid cell subpopulations, given the presence of enucleated cells within the R4 gate. (B) Bone marrow erythroid cells were isolated based on CD44 vs. Ter119 expression or CD44 expression vs. forward scatter (FSC) within the Ter119-positive subset,¹⁴ with relative abundances indicated for a representative, age- and sex-matched pair. (C) Cyclin E protein levels were determined in sorted CD44/Ter119 or CD44/FSC erythroid cell subsets shown in (B) by immunoblot (top) and quantified relative to HDAC2 (bottom).