CD28 and neoplasm: For the immune part, we focused on the TCR-mediated signaling pathway and major immune checkpoints including PD-1, PD-L1, CD28, CD80/CD86, LAG3, CTLA4, TIGIT, CD155, OX40, OX40L, 4-1BB, and 4-1BBL (expressed on T cells, tumor cells, or APCs) (Figure 1).