Structure and expression of wild-type and mutant G-CSFR on Gab2 and growth. GRprox indicates truncated proximal G-CSFR. (A) Schematic representation of wild-type and mutant G-CSFR proteins. The cDNAs for the various G-CSFR forms were engineered to express the hemagglutinin (HA) tag at the C terminus. (B) HA blotting of cell lysates from cell lines expressing the various G-CSFR forms. Cell lysates were prepared, electrophoresed, and transferred onto poly(vinylidene difluoride) (PVDF) filter. The filter was then blotted with anti-HA mAb. (C). Flow cytometric analysis of G-CSFR expression on the cell surface of transfectants. Receptor expression on the control, untransfected Ba/F3 cells are shown in the filled curves.