NQO1 protein expression in cervical lesions using IHC. (A) NQO1 protein was negative in normal cervical epithelia. (B) NQO1 protein staining was positive in dysplastic cells of CIN-3, but negative in adjacent normal cervical glands (arrows). (C) NQO1 protein showed diffuse and strong cytoplasmic-positive staining in late-stage cervical SCC. (D) NQO1 was weakly positive in early-stage cervical SCC. (E) NQO1 protein was negative in cervical SCC without metastasis. (F) This case of SCC showed a rare nuclear staining pattern.