In order to better understand how tumor necrosis factor (TNF)-α may contribute to the local regulation of uterine cell death, cultures of mouse uterine epithelial WEG-1 cells were exposed to TNF-α and observed at different time intervals. Earliest decrease in cell viability was observed after 31 h of exposure to 50 ng/ml mouse TNF-α and was associated with the expression of several markers of apoptosis. Treatment with human TNF-α or addition of a neutralizing antibody against TNF-α receptor protein 80 to mouse TNF-α resulted in attenuated induction of apoptosis, suggesting that coengagement of the two TNF-α receptor types is required for maximal impact. Ceramide analogs failed to replicate the effect of TNF-α and the stress-activated protein kinase signaling pathway was not activated by the cytokine. Treatment with mouse TNF-α resulted in an increase in nuclear factor (NF)κB activity that receded after 24 h. The impact of human TNF-α on NFκB activation was more moderate. Addition of either one of three different inhibitors of NFκB (SN50, PDTC, and A771726) to mouse TNF-α sensitized WEG-1 cells to the toxicity of the cytokine. Our data suggest that WEG-1 cells initiate their response to TNF-α with an increase in NFκB activation that may have transiently biased these cells toward cell death resistance.