FIGURE 2.

Characterization of reversibly immortalized TGMCs (iTGMCs). A, The proliferative activity of iTGMCs decreases after removal of SV40 T antigen via FLP recombinase. B, Removal of SV40 T antigen in iTGMCs confirmed by RT‐qPCR analysis 3 days after infection. (^* P < .05). C, Expression of mesenchymal and/or progenitor markers in iTGMCs. IgG and minus primary antibody staining were performed as negative controls (not shown). D, Analysis of the tumorigenic risk in vivo. SCC‐15 and iTGMCs stably expressing the firefly luciferase were injected into the athymic nude mice subcutaneously. Compared with the SCC‐15 group, no masses were detectable in the iTGMCs group at day 14. E, The average bioluminescence signals were quantitatively analysed by the Living Image software. (**P < .01). Representative results are presented