Figure 1.

Effect of PS2 knockout on the development of lung tumor. (a) Tumors were induced by a single intraperitoneal injection of 1 mg/g urethane once a week for 10 weeks. Mice were euthanized at time points up to 6 months after injection of carcinogen. At the time of killing, lungs were lavaged, perfused and fixed in ice-cold Bouin's fixative solution for 24 h. After fixation, lungs were used for surface tumor number and diameter measurements. The results are expressed as mean±s.d. (b) Lung tissues were processed and stained with haematoxylin and eosin or analyzed by immunohistochemistry for detection of positive cells for PCNA. (c) Tumor extracts were analyzed by western blotting. Samples (20 μg) were resolved on SDS–PAGE, and detected with antibodies against PCNA, MMP2, MMP9, Cyclin (B, D1 and E), Cdk (1, 2, 4 and 6), Ki67, p-pRb and β-actin. The experiments shown in Figure 1 were repeated in triplicate with similar results. *P<0.05 compared with the wild-type mice.