Caspase 2 and 3 activation is confirmed by western blotting analysis: the precursor isoforms progressively decrease after exposure to CF, while processed (active) caspase 3 becomes detectable (Fig. 3B), in parallel with an early and extensive cleavage of its endogenous substrate PARP (Fig. 3B). This evidence concerns the gene CASP2 and cystic fibrosis.