FIG 4.

Neutral Red uptake by ArtB-treated Vero cells. (A) Light micrograph showing Neutral Red dye incorporation into vacuoles by Vero cells treated with or without 10 μg/ml ArtB. (B) Dose response. Vero cells were treated with the indicated doses of ArtB for 4 h, and Neutral Red uptake was measured spectrophotometrically, as described in Materials and Methods. (C) Time course. Vero cells were treated with 10 μg/ml ArtB for the indicated times and then assayed for Neutral Red uptake. Data are A₅₄₀ values (means ± standard errors of the means from at least three experiments). (D) Dose response after 24 h of incubation. *, P < 0.05; **, P < 0.01; ***, P < 0.001 (relative to untreated [u/t] control cells, as determined by Student's unpaired, two-tailed t test).