bFGF rescues 423-cells from serum starvation-induced apoptosis downstream of activated caspase-3.

Serum withdrawal rapidly induces apoptosis in rat 423-cells, while addition of bFGF results in cell survival. However, surviving cells initially display morphological changes characteristic for apoptotic cells and even process caspases. Active caspase-3 was detected at the single-cell level in those finally bFGF-rescued cells, while mitochondrial integrity was maintained. Generation of cleavage products of caspase targets was confirmed in surviving cells. Proteome analysis indicated multi-faceted survival activities of bFGF including upregulation of inhibitor-of-apoptosis and heat shock protein family members directly interfering with caspases. Our data suggest that the "point-of-no-return" in death-induced cells has to be moved downstream of activated caspase-3.