Anti mouse or anti rabbit secondary antibodies

iKras proteins were collected from cells at all time points after Kras^G12D induction by lysis in RIPA buffer (20 mM Tris-HCl (pH 7.5) 150 mM NaCl, 1 mM Na₂EDTA, 1 mM EGTA, 1% NP-40, 1% sodium deoxycholate), supplemented with phosphatase and protease inhibitors (Thermo Fisher Scientific). Equal amounts of protein were electrophoresed on 12% SDS-PAGE gels and transferred to nitrocellulose membranes (GE Healthcare). Membranes were blocked in either 5% milk or 3% BSA for 1 hr, and primary antibody incubations were performed overnight at 4 °C with rocking. Additional file 2: Table S5 contains primary antibodies and dilutions used. Anti-mouse or anti-rabbit secondary antibodies (1:5000, Millipore) were incubated on the membranes for 1 hr at room temperature with shaking, followed by detection of bands with chemiluminescence (Thermo Fisher Scientific). Uncropped versions of all western blots are available (Additional file 1: Fig S11, Fig S12, Fig S13). Quantification of bands in three independent biological experiments was completed using ImageJ and statistical significance determined by Student’s t tests in GraphPad Prism.

Normal and EHMT1^+/‐ mutant human dermal fibroblasts were lysed in 4× Laemmli buffer (250 mm Tris (pH 6.8), 20% glycerol, 8% SDS, 0.0025% bromophenol blue, 1 mm β‐mercaptoethanol), collected by scraping with a rubber policeman and then sonicated for 10s. Samples were boiled at 95 ^⁰C for 5 min then subjected to 14% SDS polyacrylamide gel electrophoresis, transferred onto polyvinylidene difluoride membranes and probed with the following primary antibodies: anti‐H3K9me2 (Cell Signaling Technology, Danvers, MA, USA), anti‐total Histone H3 (Abcam, Cambridge, MA, USA) in 3% bovine serum albumin in TBST, or anti‐EHMT1 (Abcam, Cambridge, MA, USA) in 5% milk. Anti‐mouse or anti‐rabbit secondary antibodies (Millipore, Danvers, MA, USA) were incubated on the membranes, after three successive washes with TBST, for 1 h at room temperature, followed by detection of bands with ECL (Pierce, Rockford, IL, USA). Quantification of bands was done using ImageJ (Rasband).