TLR4 and neoplasm: Likewise, upon challenge, TLR4-deficient and wild-type mice immunized with PBS/2M urea developed palpable tumor within 10–15 days which rapidly reached large size (Fig 3B), whereas the treatment of TLR4-deficient mice with three doses of E6E7 resulted in 100% of therapeutic protection to TC-1 tumors (Fig 3B), showing that the protection does not involve LPS/TLR4 activation.