TNFSF4 and cancer: Ideally, artificial APCs (aAPCs) have been engineered to provide the following three signals for T cell activation: signal 1, presents peptide epitopes derived from cancer neoantigens through their major histocompatibility complex (MHC) to T cell receptors (TCR) on T cells; signal 2, provides costimulatory signals by facilitating the binding of CD80/CD86, OX40L, and/or 4-1BBL to their receptors on T cells; and signal 3, secretes cytokines such as interleukin (IL) 12 or IL15 to promote T cell survival, activation, and proliferation.7