In contrast, other studies have demonstrated that the loss of human leukocyte antigen (HLA) class I or β2M expression is associated with poor prognosis in breast cancer patients [18, 19], and β2M could increase the sensitivity of breast cancer cells MCF-7 to doxorubicin, and a decrease or loss of β2M expression by antisense RNA is involved in the acquisition of doxorubicin resistance [20]. The gene discussed is B2M; the disease is breast cancer.