ΔCD98hc-β geo fusion protein is present mainly in the cytoplasm. A. Wild type CD98hc (CD98hc), mutant CD98 (ΔCD98hc-β geo) or mutant CD98hc without β geo fusion (ΔCD98hc) were expressed in frog oocytes. The oocytes were sectioned and immunostained with anti-CD98hc antibody (green) for detection of CD98hc and ΔCD98hc or stained with X-gal for detection of β-galactosidase (β gal, blue) activity in ΔCD98hc-β geo. ΔCD98hc-β geo was localized mainly in the cytoplasm, although ΔCD98hc was clearly detected on the cell surface. Note that expression of ΔCD98hc-β geo is intense near the cell surface. B. X-gal staining of CD98hcΔ/+ ES cells (PST080). β gal activity (blue) that represents ΔCD98hc-β geo protein is mainly localized in the cytoplasm. C. PST080 ES cells were double-immunostained with anti-CD98hc (red) and anti-β gal (green) antibodies. Note that ΔCD98hc-β geo expression as detected by anti-β gal antibody was localized mainly in the cytoplasm. Blue staining shows nucleus. D. Histogram showing the expression levels of CD98hc and β gal in PST080 ES cells. The ES cells were fixed and immunolabeled with anti-CD98hc or anti-β gal antibody for detection by flow cytometry. No significant cell surface labeling was produced by anti-β gal antibody compared to the control antibody.