PTEN function was inhibited in 4T1-luc cells, and the growth rate was faster than that of tumors created by normal PTEN cells, the mean sizes of in situ mammary tumors in mice increased from 0.44×0.37 cm2 (length×width) of control group to 1.59×1.68 cm2 (200 nmol/L) and 1.86×1.72 cm2 (500 nmol/L), respectively (Figures 3C–E). Here, PTEN is linked to breast cancer.