A. Brequinar (BQR) induces ferroptosis in HT1080s as rescued by fer-1, and cotreatment with BQR (500 μM) increases sensitivity to RSL3 in HT1080s. Data are represented as mean ± SEM, n=3. B. Dose-response curve of HT1080 cells cotreated with 1 μM of FINO2-1, FINO2-3, or FINO2-4. Data are represented as mean ± SEM, n=3. C. HT-1080 cells treated with DMSO or IKE (10 μM) for 6 hours and stained with C11 BODIPY (oxidized and reduced overlay), CellMask Deep Red, and ERTracker Blue-White. D. HT-1080 cells treated with DMSO or IKE (10 μM) for 10 hours and stained with C11 BODIPY (oxidized and reduced overlay), CellMask Deep Red, and ERTracker Blue-White. E. Correlation (Manders coefficient) of C11 BODIPY oxidized signal with ERTracker Blue-White or MitoTracker Deep Red in HT1080 cells treated with either RSL3, IKE, FINO2, or FIN56 at designated timepoints. Data are represented as mean ± SEM, each individual point represents an image of multiple cells. Number of images for each condition are RSL3 2 hour (n=3), 5 hour (n=2); IKE 2 hour (n=7), 5 hour (n=5), FINO2 2.5 hour (n=6), 4.5 hour (n=9), FIN56 2 hour (n=6), 4 hour (n=5), 5 hour (n=2). Ordinary one way ANOVA with Tukey’s test for multiple comparisons was used with p values of: RSL3 (0.0016, 0.6120), IKE (0.0023, 0.1279), FINO2 (<0.0001, <0.0001), FIN56 (0.0034, 0.0005, >0.9999). F. Correlation (Manders coefficient) of C11 BODIPY oxidized signal with ERTracker Blue-White or MitoTracker Deep Red in HT1080 cells treated with either RSL3 (1 μM), BQR (1 mM) or both at designated timepoints. Data are represented as mean ± SEM, each individual point represents an image of multiple cells. Number of images for each condition are RSL3 1.5 hour (n=4), 2 hour (n=2); BQR 2 hour (n=3), 2.5 hour (n=3); RSL3 + BQR 1.5 hour (n=2), 2 hour (n=2). Two-sided unpaired t test was used with p values of: RSL3 (<0.0001, 0.0178), BQR (0.0006, 0.1011), RSL3 + BQR (0.0117, 0.2027). For all panels, GraphPad Prism (GP) P value style of 0.1234 (ns), 0.0332 (*), 0.0021 (**), 0.0002 (***), <0.0001 (****).