B16.F10-OVA melanoma cells (1x105) were engrafted onto the abraded skin in the flanks of Ly5.1+ mice. 24 h after tumour cell engraftment naïve CD8+CD62LhiCD44lo lymph node T cells from Ly5.2+ OT-1;Ptpn2fl/fl versus Ly5.2+ OT-1;Lck-Cre;Ptpn2fl/fl mice were adoptively transferred and tumour incidence monitored. 