(A) Probe 2 induces Bax-dependent cell death in HCT116 wild type cells, compared to HCT116 Bax/Bak DKO cells. (B) Quantification of cell death effects induced by Probe 2. Data are represented as mean +/− SD, n=3, **, P<0.01, ***, P<0.001. (C) Probe 2 induces Bax-dependent increase of ROS, while 4-HNE induce Bax-independent ROS. Data are represented as mean +/− SD, n=3, **, P<0.01. (D) Cys62 is the major site of 2-HD modification on Bax. Probe 2 partially labels Bax C62S and does not label C62/126S (2CS) mutant, while labeling wild type and C126S mutant efficiently. (E) Detection of the probe-labeled peptide containing Cys62 by mass spectrometry. Observed the m/z of 1054.635, which matches the probe-modified Cys62 in peptide KLSECLK.