CD4 and cancer: As the pNGVL4a-CRT/E7 (detox) vaccine was previously described to effectively target HPV16 E6/E7 expressing tumors in the absence of CD4 T cells in other models of HPV + cancer [63], the ability of the Kras + HPV + SONIC-induced tumors to respond to the vaccination in a CD4-deficient environment was also examined here.