Although cell fusion is an omnipresent process in life, to date considerably less is still known about the mechanisms and the molecules being involved in this biological phenomenon in higher organisms. Cell Fusion in Health and Disease Volume 2 is covering the dark side of cell fusion: namely its role in pathophysiological processes. International leading experts will present up-to-date overviews about cell fusion mediated horizontal gene transfer in bacteria and viruses, class III viral membrane fusion proteins, trophoblast fusion in trisomy 21, and the role of microvesicles in malignancies. Particular attention is paid on cell fusion in cancer and how this biological phenomenon may initiate the origin of (recurrence) cancer stem cells as well as drive the progression of multiple myeloma, colon cancer, breast cancer, and malignant melanoma. Thus, Cell Fusion in Health and Disease Volume 2 represents a state-of-the-art work for researchers, physicians or professionals being interested in reflecting the dark side of cell fusion.