Fig. 5. PBPs do not enhance the autocrine production of TNF-α in amelanotic melanoma cells. (a) Viability and (b) ROS generation in SKMel-188 cells pretreated (1 h) with neutralizing antibody (5 μg/ml) against TNF-α prior to treatment with PBPs (100 μg/ml or 200 μg/ml). (c) The mRNA expression levels of TNF-α and TNFR1 in SKMel-188 cells treated with PBPs for 24 h, as determined by quantitative real-time PCR. (d) Detection of TNFR1 expression (green) using immunohistochemical assays with SKMel-188 cells incubated with PBS (control) or stimulated with PBPs (200 μg/ml) for 48 h. Cell nuclei were counterstained with PI (red).