Splicing isoforms of adapter protein CRK, CRK-1 (CRKI) and CRK-2 (CRKII), as well as the related adapter protein CRKL can be recruited to the activated MET receptor via association with tyrosine phosphorylated GAB1 (Garcia-Guzman et al. 1999, Schaeper et al. 2000, Sakkab et al. 2000, Lamorte et al. 2000, Lamorte et al. 2002).