SLAP interacts with EpoR. (A) eGFP and eGFP/SLAP EI-11 erythroblasts were lysed, and cell lysates were immunoprecipitated (lanes 1 and 2) with an EpoR antibody and immunoprecipitated proteins subject to Western blotting analysis using either anti-Flag (top blot) or anti-EpoR (bottom blot) antibodies. Immunoprecipitated EpoR (bottom blot) and coimmunoprecipitated SLAP (top blot) are indicated by arrowheads. Whole cell lysates from eGFP (lane 3) and eGFP/SLAP (lane 4) EI-11 cells and from 293T cells transfected either with plasmids encoding EpoR (lane 5) or Flag-SLAP (lane 6) as well as nontransfected control (lane 7) were analyzed by Western blot to identify EpoR (arrowhead in bottom blot) and SLAP proteins (arrowhead in top blot). (B) 293T cells were transfected with expression plasmids for EpoR, Flag-SLAP, or cotransfected with both expression plasmids as indicated. (Top blots) Cell lysates were immunoprecipitated with EpoR-specific (left blot) or SLAP-specific (right blot) antibodies, and coimmunoprecipitated proteins were identified by Western blot using anti-Flag or anti-EpoR antibodies as indicated. Coimmunoprecipitated proteins are indicated by arrowheads. (Bottom blot) The same immunoprecipitates were analyzed by Western blot by using the same antibody as that used in the immunoprecipitation step. Immunoprecipitated proteins are indicated by arrowheads.