Increased cell attachment upon the activation of Rho proteins by CNF1 and CNFy. HeLa cells were treated with CNF1, CNFy, TcdB or buffer for 2 h and suspended by trypsin. Suspended cells were seeded onto a cell culture dish coated with fibronectin (a–c) or left uncoated (d). At the indicated time points, the medium containing nonadherent cells were removed. (a) Attached cells were documented by phase contrast microscopy. (b) The number of adherent cells per area was determined. Results displayed are the mean ± SD of three independent experiments (each experiment cells). values <0.001 (***) were considered as statistically significant as compared with nontreated cells. Cell spreading on fibronectin-coated polystyrol (c) or on noncoated polystyrol (d) was analysed in terms of the increasing number of spread per total cells. Results displayed are the mean ± SD of three independent experiments (each experiment cells). values <0.001 (***) were considered as statistically significant as compared with nontreated cells.