LCK and neoplasm: Analysis of p56lck activation status in nonlytic TIL by immuneprecipitation and reciprocal immunoblotting using Ab reactive with the phosphorylated form of the src family kinase inhibitory motif (centered on Y505) showed that this motif in p56lck was not appreciably phosphorylated upon conjugation in vitro with cognate tumor cells (Fig. 1a).