Research has shown that different strains of mice possess varying susceptibility to lung cancer. C3H and C57BL6 mice are highly resistant to lung cancer, whereas A/J and 129 mice are very susceptible to lung cancer. Data from our lab shows that the mice have different numbers of natural killer (NK) cells as well as different characteristics of those cells. C3H and C57BL6 mice have higher numbers of NK cells as well as higher expression of CD11b, whereas A/J and 129 mice have lower numbers and lower expression.