SYN1 and breast cancer: A heterotypic cell fusion assay was set up with the three different M13SV1_DSP8-11 cell lines (wild type, ASCT2KO, Syn1 overexpression) and three breast cancer cell lines (MDA-MB-231, MDA-MB-435S and HS578T) expressing the DSP1-7 vector in a ratio of 1:3 for 72 h with or without the inflammatory cytokine TNFα as stimulus for cell fusion, with subsequent analysis of the cell fusion with flow cytometry and microscopy (Figure 7).