Moreover, due to their limited affinity for DNA through their own MH1 domain, R‐Smads need to collaborate with other DNA‐binding cofactors to achieve high affinity for DNA and selectivity for specific genes.[11] Considering the critical role of TGF‐β in tumor metastasis, targeting specific cofactors would be an effective strategy for inhibiting breast cancer lung metastasis. This evidence concerns the gene TGFB1 and breast cancer.