As an essential anti-apoptotic protein, Bcl-2 has a particular expression in cells under normal circumstances; when the word of Bcl-2 decreases, it may promote the apoptotic response of anti-cancer drugs; while when the word of Bcl-2 increases, it may lead to resistance to chemotherapeutic drugs, radiotherapy, and other anti-tumor therapy. The gene discussed is BCL2; the disease is neoplasm.