We previously demonstrated caspase-mediated cleavage of p130cas during apoptosis and identified two caspase-3 cleavage sites [1]. In this study. we investigated the phosphorylation-dependent cleavage of p130cas in apoptotic Rat-1 fibroblast cells. Lysophosphatidic acid and fibronectin induced p130cas phosphorylation. which in turn resulted in resistance to caspase-mediated cleavage. Alternatively, dephosphorylation by calf intestinal alkaline phosphatase, PPL and LAR stimulated cleavage of p130cas by caspase-3, generating a 31-kDa fragment. During apoptosis, p130cas dephosphorylation seems to precede its cleavage. The phosphorylation of tyrosine and serine residues immediately adjacent to the two cleavage sites (DVPD416 and DSPD748) strongly affected p130cas cleavage by caspase-3, both in vitro and in vivo. Furthermore. the generation of the 31-kDa cleavage fragment was strongly regulated by phosphorNlation of a tyrosine residue at position 751 (DSPD748 and GQY(751)). Our results collectively suggest that degradation of p130cas during apoptosis is modulated in a phosphorylation-dependent manner. (C) 2002 Elsevier Science (USA), All rights reserved.