Fig. 3

C-MYC overexpression promoted proliferation of MSC. Cell proliferation kinetics was assessed by recording cumulative cell numbers (a) and the population doubling number per day (PDN) (b) in GFP- or c-MYC-MSC at every passage during expansion (passages 1 to 15); n = 4; *P < 0.05 (ANOVA test). c GFP-MSC and c-MYC-MSC were mixed (4:1, respectively) after passage 4 and co-cultured for four passages. Left: representative images of mixed GFP/c-MYC- or control GFP-MSC at the start of the co-culture (passage 4) and after passage 8. DAPI was used for nuclei staining; Scale bar, 100 μm; right: quantitative analysis of GFP-positive cells in GFP/c-MYC co-cultures, and pure GFP- or c-MYC-MSC cultures, done by flow cytometry. Proportion of GFP-positive cells in corresponding cell populations was quantified in relation to the pure GFP population at passage 4 (set as 1). Asterisks indicate significant differences in comparison to GFP-MSC at passage 4; n = 4; *P < 0.05