The rapidity of inhibition of TCR signaling mediated by pcdh18 is characteristic of ISR expressed in immune cells, thus, within seconds of recognition of cognate tumor cell, p56lck in anti-MCA38 TIL becomes inactive, therefore Zap70 is not activated and all downstream signaling is prevented which abrogates the effector phase. This evidence concerns the gene PCDH18 and neoplasm.