RabGEF1's coiled coil and Vps9 domains regulate basal surface expression of FcϵRI and β₁ integrin. Basal surface expression levels of (A) FcϵRI and (B) β₁ integrin were analyzed on the indicated mast cell populations by flow cytometry, as described in Figure 1B. Values were pooled from 4 separate experiments. * indicates P < .05 versus assigned −/− value of 100%.