Figure 4 Expression of 774del4 and 818del4 mutant IFNγR1 proteins by transfected cells. Expression constructs carrying the wild‐type (WT), 774del4, and 818del4 forms of IFNGR1 were transiently transfected into HEK 293 cells using the calcium phosphate method. IFNγR1 protein was detected by Western blotting. The WT IFNγR1 (B) was detected with an apparent molecular weight of 80–95 kDa. The 774del4 (C) and 818del4 (D) mutant forms of IFNγR1 gave strong signals with an apparent molecular weight of 45–60 kDa; this band was not detected in the WT‐transfected cell lysate. IFNγR1 was not detected in the total lysate of cells transfected with the mock vector (A).