Flagellin activates LSK cell proliferation indirectly. Whole bone marrow cells from CD45.1⁺ WT and CD45.2⁺ N4T5-DKO mice were mixed in a 1:1 ratio and incubated in complete RPMI or RPMI containing 50 ng/mL flagellin for 15 hours, followed by 1-hour labeling with 10 µM BrdU. Cells were analyzed by flow cytometry as in Figure 1. Representative flow cytometry plots comparing LSK proliferation (A), LSK cell percentage in BM (B), LSK cell number in bone marrow (C), and BrdU incorporation (D) for PBS vs flagellin-treated mixed cell culture. Statistics were analyzed by unpaired Student t-test, error bars depict SEM. ***P ≤ .001.