Effects of black raspberries on cellular events and associated genes in the N-nitrosomethylbenzylamine (NMBA)-treated rat esophagus. PCNA, proliferating cell nuclear antigen; COX-2, cyclooxygenase-2; PGE2, prostaglandin E2; TUNEL, terminal deoxynucleotidyl transferase dUTP nick end labeling; iNOS, inducible nitric oxide synthase; NF-κB, nuclear factor kappa B; VEGF-1, vascular endothelial growth factor-1; HIF-1α, hypoxia-inducible factor-1α.