Figure 8.

Effect of short-term hormone treatment on mammary cancer multiplicity in the activated Her-2/neu transgenic mice. The group of mice (n = 21) treated with estradiol alone developed a total of 13 mammary tumors and the group of mice (n = 24) treated with estradiol plus progesterone developed a total of 20 mammary tumors by 8 to 9 months of age; in comparison, the group of control mice (n = 20) developed a total of 136 mammary tumors (p < 0.005). Results are expressed as means ± SEM.