We carried out protein thermal shift assay to directly confirm the binding between NSD2-PWWP protein and compound 38. As shown in Figure , compared to DMSO control, the melting temperature (Tm values) of NSD2-PWWP1 protein was evidently increased due to the addition of compound 38 and the change of melting temperature (Tm) in a dose-dependent manner at concentrations from 0.781 μM to 200 mM. The results indicated that the ligands directly bind to NSD2-PWWP protein and could strengthen its stability in vitro. We further evaluated the target binding specificity of compound 38 using the thermal shift assay. Our results show that compound 38 exhibited remarkable selectivity against NSD2-PWWP1 protein over other PWWP domains protein (NSD3-PWWP1, DNMT3A-PWWP, ZCWPW1-PWWP).