A cell-permeable quinoline compound that selectively targets ArfGEF GBF1, but not BIG1/2, and attenuates GBF1-mediated cellular vesicle traffickings in a reversible manner. Phenotypic comparisons in Vera (African Green Monkey Kidney epithelial) cultures reveal that selective blockage of GBF1 function by GCA (100 µM) or by FGB1-E794K dominant-inactive expression affects medial- and cis-Golgi similarly to that seen with BFA (Cat. No. 203729), however, the non-GBF1-specific BFA (10 µg/ml or 35.6 µM) causes additional GBF1-independent morphologic effects on TGN, notably the rapid dispersal of Golgi-associated coat proteins AP-1 and GGA3, which are not seen with GCA treatment. Endocytic/retrograde transport studies using GCA establishes that GBF1 function is not required for the transport of bacterial toxins to the endosomes, however the retrograde transport of StxB (shiga toxin B subunit) from endosomes to TGN and Golgi is GBF1-dependent (100% inhibition of StxB sulfation at 10 µM), accounting for GCA's (10 µM) ability to completely prevent Vera cells from Stx-induced (up to 100 ng/ml) inhibition of cellular protein synthesis.