TNF and neuroblastoma: We evaluated the expression of HERVs (HERV-K env, HERV-K gag, HERV-W env, and HERV-H env) and cytokine gene expression (IL-1, IL-6, and TNF-α) in neuroblastoma (SH-SY5Y), HEp-2, and Caco-2 cell lines under simulated μg and 1g conditions.