To further confirm the potential desumoylation function of SENP2 on Smad4, we created SENP2 knockdown MDA-MB-231 breast cancer cell line (MDA-MB-231-2B) by CRISPR-Cas9 approach (Fig. 1G, lanes 1-2 and S1D). The gene discussed is SMAD4; the disease is breast carcinoma.