GM-CSF, IL-3, and erythropoietin induce the association of Crkl with STAT5. (A) (Upper panel) TF-1 cells were lysed before (pre) and after exposure to GM-CSF or IL-3 (100 ng/mL for 5 minutes). Crkl immunoprecipitates were resuspended in SDS-sample buffer. Proteins were separated by 10% SDS-PAGE and transferred onto PVDF membranes. Immunoblots were probed with an anti-STAT5 MoAb and bands were visualized by chemiluminescence. (Lower panel) The same PVDF membrane used in (A) was stripped of the antibody and reprobed with anti-Crkl antisera. The arrows indicated the relative position of STAT5, heavy chain of IgG, and Crkl. GM, GM-CSF. (B) Association of Crkl with STAT5 in UT7/EPO cells stimulated by erythropoietin. The same as in Fig 4A, except that UT7/EPO cells were stimulated by erythropoietin (10 U/mL for 10 minutes). EPO, erythropoietin.