Human breast cell growth. Human breast cancer cells and immortalized normal breast epithelial cells (1x103) were seeded in triplicate in their culture media, and quantified for their growth between 1 and 4 days following cell seeding. Cell numbers were calculated from standard curves with known numbers of cells. Results are presented as mean ± SEM from 4 independent experiments. * indicates statistical differences between normal and malignant cells at P < 0.05.