UBC9 is the only E2 enzyme for Small Ubiquitin-like Modifier (SUMO), which can also target the UBC9 promoter region to up-regulate SUMOization to regulate Foxp3+ Treg cell function after phosphorylation modification of the Y342F site of Foxp3 in human breast cancer cells (56). The gene discussed is FOXP3; the disease is breast carcinoma.