CTLA4 and neoplasm: PD-1, CTLA-4, LAG3, TIM3, BTLA, and TIGIT are some of the common immune checkpoints that mediate tumor cell recognition by T cells; when the immune checkpoint proteins present on T cells’ surfaces recognize and bind to the tumor cells’ receptors, they send an “off” signal to the T cells and hence prevent the eradication of cancer cells by the immune system.