LYN and leukemia: While in vivo manipulation of Lyn through knockout (Lyn−/−), inactivation (LynMld4/Mld4, [38]), and hyper-activation (Lynup/up) mouse models have not provided strong evidence for this kinase having a primary role in initiating neoplasia, substantial evidence does exist implicating it in regulating cancer/leukaemia cell biology [37,55,73-76].