Figure 1From: Cancer resistance of SR/CR mice in the genetic knockout backgrounds of leukocyte effector mechanisms: determinations for functional requirements SR/CR Mice Do Not Require Perforin to Survive S180 Challenges. SR/CR mice were bred into the perforin (Prf) knockout background. Progeny that survived two challenges with S180, remaining healthy and cancer free, were considered resistant. Similar survival rates were seen for the BC Prf+/- and Prf-/- mice.Back to article page