IFNB1 and melanoma: Thus, Mel Il and mel Z cell lines were undergoing the characteristic apoptotic DNA fragmentation, confirmed by Annexin V staining, while mel Ibr and mel Mtp melanoma cells may have defective apoptotic pathways and were killed by an inflammatory cell death mechanism leading to the production of a mature pro-inflammatory cytokine IL-1β via the caspase-1-independent pathway disregarding their ability to induce IFN-β expression.