Anti flag m2 mab conjugated agarose beads

3xFLAG-tagged full-length, ΔN (2–119 aa deleted), Δcoiled-coil (225–283 aa deleted) and ΔPHD domain (331–393 aa deleted) Phf23 cDNA were cloned into retroviral construct MSCV-IRES-mCherry, and transduced into Ba/F3 cells. mCherry⁺ cells were sorted out by FACS (Aria III, BD Biosciences). Then, the whole cell lysates were extracted with cell lysis buffer (Cell Signaling Technology) supplemented with protease inhibitor cocktail (Roche) and incubated with anti-FLAG M2 mAb-conjugated agarose beads (Sigma-Aldrich Cat# A2220, RRID:AB_10063035). For endogenous PHF23 co-immunoprecipitation, 10⁷ Hela cells were lysed and incubated with IgG or PHF23 antibody. The horseradish peroxidase (HRP)-conjugated FLAG antibody was purchased from Sigma (Sigma-Aldrich Cat# A8592, RRID:AB_439702), the anti-SIN3A antibody was from Thermo Fisher Scientific (Cat# PA1–870, RRID:AB_2187625), the anti-HDAC1 antibody was from Cell Signaling Technology (Cat# 34589, RRID:AB_2756821), the anti-PHF23 antibody, recognizing its C-terminus, was from Bethyl (Cat# A302–320A, RRID:AB_1850230) for Co-IP and western blotting, the anti-IgG antibody was from Abcam (Cat# ab171870, RRID:AB_2687657), the anti-GAPDH antibody was from BioXcell (BX-008) and horseradish peroxidase (HRP)-conjugated actin antibody from Thermo Fisher Scientific (Cat# MA5–32540, RRID:AB_2809817).