FIG. 7.

Loss of KSR expression inhibits tumor formation in mammary epithelial cells mediated by polyomavirus MT. Female littermates were genotyped for transgenic expression of polyomavirus MT (MT⁺) and KSR status (either KSR^+/− or KSR^−/−). These mice were examined for the development of mammary tumors starting at the age of 3 weeks. Tumors were detected by palpating all five pairs of mammary glands on each mouse daily. The onset of tumor formation in MT⁺ KSR^+/− mice (n = 9) was 35 ± 8 days. The onset of tumor formation in MT⁺ KSR^−/− mice (n = 8) was 65 ± 9 days.