To identify interacting proteins of NSD3, nuclear extracts of control H520 and H520 stably expressing Flag-NSD3 were incubated with anti-Flag M2 affinity gel (sigma #A2220) for 4 h at 4 °C, then washed and eluted with 3×Flag peptides. Silver staining was performed according to the manufacturer’s instructions (Beyotime #P0017S). The specific bands were excised for identification by mass spectrometry.