MKI67 and neoplasm: used macrophages to phagocytose calcium integrin binding protein‐1 (CIB1)‐siRNA lipoplexes and horizontally transferred this payload into the orthotopic MDA‐MB‐468 human breast tumor, resulting in down‐regulation of proliferation and survival‐promoting CIB1 and KI67 gene expressions in MDA‐MB‐468 tumor cells, thereby inducing great suppression of tumor growth.[234] To avoid the premature release of drugs and toxicity to host cells, the NIR‐responsive macrophage‐based delivery system was developed.