The invention provides a method of treating a disease or pathological condition resulting in apoptotic cell death. The method includes increasing the activity of Bcl-2 in cells affected by the disease or pathological condition. Diseases or pathological conditions can include, for example, neurodegenerative diseases, cancer and viral infections. Also provided is a method of prolonging the in vivo survival of transplanted cells for the treatment of a disease or pathological condition. The method includes increasing the activity of Bcl-2 in a population of cells and transplanting the population of cells having increased Bcl-2 activity into a subject. Diseases or pathological conditions can include, for example, neurodegenerative diseases, cancer and viral infections. A method to enhance the sensitivity of malignant cells to therapy is provided that includes decreasing the activity of Bcl-2 in the malignant cells. Methods to identify compounds that alter apoptotic cell death and to enhance monoclonal antibody production are also provided by the invention disclosed herein.