FIG. 2.

Actin stabilization directly activates Ras signaling and apoptosis. (A) The effect of the addition of 60 μM LAT-A to growth medium at the time of inoculation on F-actin organization and ROS accumulation in Δend3 cells was observed. The localization of Ras2p was also investigated in Δend3 cells grown to stationary phase with and without 60 μM LAT-A by using immunofluorescence. (B) F-actin was visualized by rhodamine-phalloidine staining and the presence of ROS was assessed by staining with H₂DCF-DA in Δend3 cells, which were either untreated or treated with 60 μM LAT-A and allowed to grow to early stationary phase. Merged images of F-actin and ROS are also presented. Bar = 10 μm. (C) The effect of LAT-A treatment on cell death was investigated using flow cytometry to measure propidium iodide uptake and ROS accumulation in treated and untreated Δend3 cells. As a positive control to demarcate the necrotic cell fraction, Δend3 cells which had been heat treated at 80°C for 2 min were also stained. (D) A viability study was carried out with cells to assess the effects of the addition of 60 μM LAT-A to Δend3 cell cultures grown to stationary phase.