BTLA and neoplasm: As BTLA regulates several downstream signaling pathways including PI3K/AKT, NF-κB, and ERK1/2 in T or B cells [15,16,24,38], and to further examine whether these signaling pathways are regulated by BTLA expressed on tumor cells, we performed the RNA sequencing (RNA-Seq) of BTLA knockdown (KD) cells.