Time course of phosphorylation of GSK3, Akt, and MAP kinase in primary human erythroblasts after growth factor withdrawal and re-exposure to Epo or SCF.

Primary human erythroblasts on day 6 of culture were either lysed direct from culture (DFC) or were washed and incubated in medium without growth factors for 2 hours (0*). Cells were then stimulated with either Epo 20 U/mL or SCF 100 ng/mL as indicated. Cell lysates were resolved using SDS-PAGE and probed on Western blot membranes using the indicated phosphospecific antibodies. The time course of phosphorylation of GSK3 (A) and Akt and MAP kinase (B) in a representative experiment of 4 performed is shown.