Abnormalities in TCR-associated molecules, especially ζ chain and p56lck, have been consistently reported in several investigations carried out on TIL or TAL obtained from cancer patients (Finke et al, 1993; Nakagomi et al, 1993; Lai et al, 1996; Rabinowich et al, 1996), as well as tumour-bearing mice (Mizoguchi et al, 1992). This evidence concerns the gene LCK and cancer.