Fig. 1

Elevated proliferative potential and sustained telomerase activity in MDA-hyb1 and MDA-hyb2 cells. a Proliferative capacity of the different breast cancer populations was tested by cell counting of initially seeded 2.5 × 10³ cells in 24-well plates after 72 h to 120 h, respectively. All tumor cell cultures progressively increased in cell number over time. A significantly elevated 10-fold enhanced proliferation for MDA-hyb1 and a 4-fold increased cell growth for MDA-hyb2 hybrid cell population were observed as compared to their wildtype MDA-MB-231 tumor counterpart. Data represent the mean + s.d. of 3 independent experiments. b and c Telomerase activity was measured in hybrid populations at different ages including MDA-hyb1 after 142d, 298d, or 501d in culture, respectively and MDA-hyb2 in passage 10 (P10), P30, or P50, respectively, in comparison to the parental MSC051212^GFP P4 and MDA-MB-231^cherry cells. A primer/dimer control and a heat-inactivated telomerase in MSC samples served as an appropriate negative control in the assays