SMAD3 and neoplasm: Ectopic expression of the SMAD3 2KQ mutant, but not WT, not only rescued KAT6A KD‐inhibited tumor growth (Figure 5F,G), lung metastasis (Figure 5F,H,I), markedly reduced the animal survival (Figure 5J), but also promoted MDSCs recruitment to lung tissues (Figure 5K; Figure S7G, Supporting Information) and primary tumor (Figure S7H, Supporting Information), CD4+/CD8+ T cells depletion (Figure 5L,M; Figure S7G, Supporting Information) in metastatic lung tissues.