Anchorage-independent growth. APM, VGA and CPR cells were seeded in suspension in complete medium containing 10% FCS. At 4 days, cell nuclei were stained with propidium iodide, photographed and the spheroids formed were evaluated. Values were obtained from duplicate measures, in three independent experiments. Representative pictures are shown. The difference among clones was statistically significant. a p < 0.001 vs CPR cells, b p < 0.01 vs VGA cells, c p < 0.05 vs VGA and CPR cells. ANOVA/Bonferroni's tests.