FIG. 1.

Serine protease inhibitors influence the uptake of CNF1 into the cytosol. The uptake of CNF1 into the cytosol was detected by the CNF1-induced deamidation of RhoA. HeLa cells were treated with 400 ng/ml CNF1 in the presence or absence of a serine protease inhibitor cocktail (PI) for 4 h at 37°C, and photographs were taken (A). As negative control, CNF1 was added to the cells in the presence of bafilomycin A1 (Baf A), which inhibits acidification of the endosomes and thus uptake of CNF1. Subsequently, the cells were lysed. Deamidation of RhoA was detected by the shift of the GTPase in SDS-PAGE in a Western blot with an antibody against the GTPase (B). The experiment was repeated more than three times with similar results.