c-Myc and SREBP1 regulation in Fbw7-null cells. (A) Lysates from two independent sets of targeted Hct116 cells were immunoblotted for c-Myc or Grb2 (see Fig. 3 A for Grb2 panel). (B) Fbw7 knockout Hct116 cells were treated with cycloheximide as indicated, and lysates were immunoblotted for c-Myc. (C) Real-time PCR analysis of c-Myc mRNA in the indicated Hct116 cells. Results are expressed as relative to wild-type Hct116 cells. Error bars show standard deviation (three replicates). (D) Lysates from the indicated Hct116 cells were immunoprecipitated with anti-SREBP1 antibody and immunoblotted for either total SREBP1 (left) or pT426 SREBP1 (right).