Cell to cell fusion occurred after doxorubicin treatment. A: MCF-7/pcDNA3-EGFP/YB-1 and MCF-7/pDsRed2-N1/YB-1 cells were co-cultured (1 to 1 ratio) without doxorubicin, (B) co-cultured with 10 nM doxorubicin. Arrow heads indicate fusion events (merged colour of green and red). C: Doxorubicin induced YB-1 overexpression; each cell lysates from (A and B) were separated by 10% SDS-PAGE, visualized by Western blot using YB-1, tubulin specific antibodies and secondary antibody (anti-mouse) with chemiluminescent substrate. D and E: FACS isolation of fused cells from the co-cultures, gated first (R1) for their size, then the gated merged colored cells (R2) were sorted. GFP fluorescence is plotted on the x-axis (FL1-Log_Height), while red fluorescence is plotted on the y-axis (FL2-Log_Height). The cells (gated R1) represent for the relatively large size of cell population. Double positive cells are gated in R2 region represent hybrids.