To study the function of RhoGDIs in this process, we used the rat basophilic leukemia cell line RBL-2H3 as a mast cell model.34 Three RhoGDI isoforms are encoded in the mammalian genome, RhoGDI1, RhoGDI2, and RhoGDI3. This evidence concerns the gene ARHGDIB and acute basophilic leukemia.