CD28 and non-small cell lung carcinoma: For example, CD80 and CD86 can bind to CD28, thereby providing positive co-stimulatory signals to promote the proliferation and survival of tissue-resident immune cells (45); PD-L1 and PD-L2 can bind to PD-1(programmed death protein 1), thereby providing negative co-stimulatory signals to inhibit the proliferation and survival of tissue-resident immune cells, promoting NSCLC (46, 47).