A cell fate can be reversed using three different cellular or nuclear reprogramming methods. In somatic cell nuclear transfer or SCNT, a nucleus from a somatic cell is grafted into an enucleated oocyte. Transcription factors present in the oocyte cytoplasm promote the expression of embryonic genes and trigger cell division to generate a blastocyst. The inner cell mass of the blastocyst serves as a source of pluripotent stem cells, which can give rise to specialized cell types. In cell fusion, two different types of cells are artificially fused together using electric pulses, generating a hybrid cell that displays a combined phenotype. For example, the fusion of a B cell, a lymphocyte, with a myeloma cell, a cancerous plasma cell, generates a hybrid cell that can both proliferate indefinitely and produce antibodies. In the transcription factor transduction method, retroviral vectors are used to deliver genes, such as Oct4 and Sox2 to the somatic cells. The expression of these transcription factors transforms the somatic cell into an induced pluripotent stem or iPS cell.