Since Mf4/4 are highly susceptible to infection with ERA, we analysed lysates of ERA virus-infected Mf4/4 by western blotting at 24 and 48 hpi using antibodies against different caspases and the pro-apoptotic peptide truncated Bid (tBid). The gene discussed is FGF16; the disease is enthesitis-related juvenile idiopathic arthritis.