Figure 4.

Reversibility of K-ras^G12V-induced ROS generation and mitochondrial dysfunction. (A) T-Rex cells were treated with 20 ng/ml doxycycline for 24 h (Tet/on), followed by withdrawal of doxycycline from cell culture for 1, 2 and 3 days. Expression of K-ras, SOD2, catalase and β-actin was measured by western blot analysis. (B) K-ras induction (Tet/on) caused an increase of ROS. Removal of doxycycline for 2 days reversed ROS increase. (C) K-ras induction caused a decrease of mitochondrial transmembrane potential. Removal of doxycycline for 2 days reversed such decrease to baseline comparable to that of the control (Tet/off). (D) Morphology of HEK293 cells without K-ras^G12V expression (Tet/off), with K-ras^G12V expression for 1 day (Tet/on), and after withdrawal of doxycycline for 2 days.