The human ZAP70 gene carrying a tyrosine to phenylalanine substitution at position 319 (Y319F) was used as the transgene. The transgene is expressed in thymocytes under the control of mouse Lck promoter and contains a hemagglutinin epitope tag at the N-terminal end and a human growth hormone polyA tail. Transgene expression was verified by Western blot analysis. (J:71098)