MKI67 and neoplasm: Consistent with the in vitro assay results, knockdown of ELK4 suppressed tumor growth in vivo, as indicated by the decreased size and weight of ELK4 knockdown xenograft tumors compared with control group tumors and the decreased number of Ki67‐positive cells in ELK4 knockdown xenograft tumors (Figure 1B; Figure S1E, Supporting Information); in contrast, ELK4‐overexpressing promoted tumor growth in vivo (Figure S1D,E, Supporting Information).