Preface, Thomas Dittmar, Kurt S. Zänker (Witten/ Herdecke University, Witten, Germany); 1 Introduction. Thomas Dittmar, Kurt S. Zänker (Witten/ Herdecke University, Witten, Germany); 2 Horizontal gene transfers with or without cell fusions in all categories of the living matter, Joseph G. Sinkovics (University of Florida, Tampa, FL, USA); 3 Class III viral membrane fusion proteins, Marija Backovic (Pasteur Institute, Paris, France), Theodore S. Jardetzky (Stanford University School of Medicine, Stanford, CA, USA); 4 Human trophoblast in trisomy 21: a model for cell-cell fusion dynamic investigation, André Malassiné, Guillaume Pidoux, Pascale Gerbaud, Jean Louis Frendo, Danièle Evain-Brion (Inserm, Paris, France); 5 Cell fusion and hyperactive osteoclastogenesis in multiple myeloma, Franco Silvestris, Sabino Ciavarella, Sabino Strippoli, Franco Dammacco (University of Bari, Bari, Italy); 6 Cell fusion hypothesis of the cancer stem cell, Xin Lu, Yibin Kang (Princeton University, Princeton, NJ, USA); 7 Expression of macrophage antigens by tumor cells, Ivan Shabo, Joar Svanvik (Linköping University, Linköping, Sweden); 8 Leukocyte-Cancer cell fusion: Initiator of the Warburg effect in malignancy? Rossitza Lazova, Ashok Chakraborty, John Pawelek (Yale University School of Medicine, New Haven, CT, USA); 9 Cell fusion, drug resistance and recurrence CSCs, Christa Nagler, Kurt S. Zänker, Thomas Dittmar (Witten/ Herdecke University, Witten, Germany); 10 The role of microvesicles in malignancies, Erna Pap (Semmelweis University, Budapest, Hungary); Index