S100A1 and escherichia coli infection: Among them, genes associated with immune responses, such as Mpo, Ccl3, and S100A calcium‐binding proteins S100a8 and S100a9, were specifically expressed in mBM‐MK5 (Figure S5I, Supporting Information), confirming the existence of mouse “immune MKs.” Consistent with our earlier results from the human and mouse models, the percentage of immune MK subpopulation (mBM‐MK5), which could also be identified through the specific expression of Cd48, increased substantially after E. coli infection (Figure 5F,G).