Fig. 4. The vFLIP-IKK kinase activity is inhibited by geldanamycin. Cytoplasmic extract from 293T cells transduced with a lentivirus encoding either vFLIP plus GFP (A,B) or GFP alone (C) and then treated with DMSO or geldanamycin (GA), as indicated, was subjected to gel filtration on a Superose 6 column. Fractions were analysed by immunoblot with anti-vFLIP or anti-IKK antibodies; in A and B fractions were also immunoprecipitated with the anti-vFLIP antibody 6/14 and IB kinase activity was measured.