ESR1 and neoplasm: IHC staining with antibodies against Smyd3, H3K4me3, and Ki67 revealed that the protein levels of Smyd3, H3K4me3, and Ki67 were dramatically decreased in tumor slices treated with BCI-121 (Fig. 5c, d and Supplementary Fig. 6c, d), suggesting that the inhibition of Smyd3 could disable the downstream oncogenic actions potentiated by Smyd3 and ERα.