ESR1 and breast carcinoma: Since HR+ BC is the most common subtype with a better prognosis than HR− BC, we also found that ER or PR-negative breast cancer tissues or cells had higher levels of UBE2S and UBE2C and lower expression of Numb compared with HR+ breast cancer, providing evidence for the promoting roles of UBE2S and UBE2C and the suppressive role of Numb in breast cancer malignancy.