CD4 and neoplasm: DAMPs released from tumor cells are sensed by antigen presenting cells (APCs) to present antigens to T cells to stimulate adaptive immunity.[39] APCs expressing major histocompatibility complex (MHC) proteins can stimulate CD4+ helper T cells as well as cytotoxic CD8+ T cells.[40, 41] Bone marrow derived dendritic cells (BMDCs) were co‐incubated with 4T1 cells pre‐treated with CuP, Er‐NCP, or CuP/Er to evaluate DC maturation and the expression of MHC II proteins induced by the DAMPs from treated 4T1 cells.