NIH/3T3 cells were cultured at least 2 weeks in light medium: DMEM for SILAC (Thermo scientific) supplemented with PS, dialyzed FBS (Thermo scientific), (light) L-Lysine-2HCl (0.666 mM), (light) L-Arginine-HCl (0.399 mM)44, and L-Proline (200 mg/L). Before switching from light to heavy medium, cells were treated with 0.05 µg/mL CHX or equivalent dilution of DMSO in 6-well plates. At timepoint 0 h, we replaced light medium with pre-warmed heavy medium: DMEM for SILAC (Thermo scientific) supplemented with PS, dialyzed FBS (Thermo scientific), (heavy) 13C6 15N2 L-Lysine-2HCl (0.666 mM), (heavy) 13C6 15N4 L-Arginine-HCl (0.399 mM), and L-Proline (200 mg/L) for NIH/3T3.