Immunofluorescence analysis of brain tissues sections showed that the signals carried by the RMPs‐R4F or P5091@RMPs‐R4F could co‐localize with F4/80+CD206+ M2Φ, demonstrating that RMPs‐R4F can effectively cross BBB and target tumor‐infiltrating M2Φ/microglia (Figure 4B). This evidence concerns the gene MRC1 and neoplasm.