Figure 4. Glutamine controls clonal heterogeneity in MCF-7 cells. MCF-7 cells were cultured at low density in the presence (4 mM and 2 mM) or in the absence of glutamine. (A) Representative phase contrast microscopy images of holoclones, meroclones and paraclones. Holoclones are large colonies with compact and smooth borders, while paraclone are small colonies with flattened shape. An intermediate phenotype characterizes meroclones. Phase contrast microscopy images were captured using Canon powershot G6 camera at 10× magnification, 6× digital zoom. (B) After 10 days of culture, the number of holoclones, meroclones and paraclones were counted. Relative percentage of colonies is shown. Data are mean ± S.D. of three independent experiments.