We have been using HaCaT cell line in our lab for long to check cytokine secretion (IL-6, IFN-y etc) by LPS/TNF-alpha secretion.
However now the cell line is not responding to LPS/TNF-alpha. There is no increase in secreted levels of these cytokines after stimulation. However, the cell line is still sensitive to anti-proliferative drugs...
What can be the possible reasons and how to solve this?