Effect of hypoxia on lung metastasis of Lewis lung carcinoma in mice. On the fourth day after cancer cell injection, the animals were placed under 10% hypoxia for 17 days (total of 3 weeks). After hypoxia exposure, the mice were sacrificed and lung metastasis nodules were counted. (A) Number of metastatic nodules in mouse lungs, (B) Representative lungs showing metastatic nodules the lungs. More and bigger metastasis nodules were seen in hypoxic mouse lungs than in normoxic lungs (arrows). (C) Quantitative data on primary tumor weight. *p < 0.05 as compared with normoxia. n = 10 mice for each group.