CD274 and cancer: Cancer is a complex disease involving various cells and their membrane interactions in the tumor microenvironment, such as immune suppression via PD-1/PD-L1 axis in T cells, recruitment of stem cells via membrane receptor-mediated CXCR4/CXCL2 chemokine axis, maturation of immune cells via membrane interactions, and various other chemical interactions, which uncover the potential of using cells in cell- and cell membrane-based drug delivery.