“…In adult mice, the majority of the splenocytes do not reproduce vigorously, thus transient Cre activities fail to induce recombination effectively in the nongrowth or nondivision somatic cells. These results suggested that as a protein delivery tool, the Bac‐T3SS is suitable for in vivo delivery of transiently functional proteins, opening up the possibility of wide applications such as transcriptional factor delivery for somatic cell reprogramming (Bai et al, ; Bichsel et al, ), tumor antigen for antitumor immunotherapy (Wang et al, ), pathogenic antigen or epitope for anti‐infectious disease vaccines (Russmann et al, ; Rüssmann et al, ), and signaling molecules for intracellular signal transduction (Ittig et al, ). Again, high efficiency, low cost, and ease of manipulation make this protein delivery tool especially attractive for various cellular manipulations for biomedical applications.…”