**Figure 3.** **Correlation analysis.** (**A**) Representative microphotographs of fibroblasts immunofluorescently labeled for Ki67. (Ki67+ cells are marked with arrows), (**B**) The fraction of Ki67+ cells in mass culture vs. four indicated clonogenic endpoints; all correlations, except for a correlation with the dense colony fraction (p=0.07), were statistically significant at p<0.05, (**C**) The fraction of diffuse colonies (X-axis) vs. the other endpoints (Y-axis, as indicated). **(D**) The fraction of Ki67+ cells (X-axis) in mass culture and the other endpoints (Y-axis, as indicated). Note: Red color indicate a trend-line with the *r* value that is not statistically significant (p=0.07). The *r* values colored in black are statistically significant (*p*<0.05).