Immunoprecipitations were carried out as described (46 (link)) using anti-MSX2 (HPA005652, Sigma-Aldrich) anti-ARID1A (12354, Cell Signaling), anti-SMARCA4 (ab110641, Abcam), anti-trimethyl histone H3 (Lys27) (07-442, Merck Millipore), anti-trimethyl histone H3 (Lys9) (07-449, Merck Millipore), and anti-histone H3K27 (ACM-39685, Active Motif/THP) antibody; for details, including the bioinformatic analysis, see SI Appendix.