a. IMR90 cells transfected with FLAGKlhl12, FLAGKlhl12FG289AA, or FLAGKeap1 were analyzed by confocal microscopy (BTB, green; collagen-I, red; DNA, blue). When noted, cells were treated with chloroquine, MG132, brefeldin A (BFA), or dialyzed medium lacking ascorbate. Errors: standard deviation, n=3. b. Cell lysate (L) or culture medium (M) of IMR90 cells transfected with FLAGKlhl12, or FLAGKlhl12FG289AA was analyzed by immunoblotting. c. Collagen-I localization was analyzed IMR90 cells expressing Klhl12, after re-addition of ascorbate. d. HT1080 cells stably expressing collagen-I were transfected with shRNAs against Cul3 and analyzed by confocal microscopy (transfection control GFP, green; PDI, blue; collagen-I, red). Error bars: standard deviation, n=3. e. D3 mESCs were treated with control siRNAs or siRNAs targeting Cul3 or Sec13 and analyzed by confocal microscopy (collagen-IV, green; actin, red; DNA, blue).