Expressed in lymph nodes, thymus and spleen;Through ITIM, it recruits SHP-1 or SHP-2, which act as phosphatases and dephosphorylate tyrosine, which inhibits immune activation;Has a Grb-2 recognition motif which, when recognized by the Grb-2 protein, promotes PI3K activation and additionally mediates cell proliferation and survival;High BTLA expression may predict poor prognosis in NSCLC patients. This evidence concerns the gene BTLA and non-small cell lung carcinoma.