HSPCs were pre-incubated with specific inhibitors impacting MkMP uptake by HSPCs. The inhibitors used were methyl-β-cyclodextrin (MβCD), dimetylamiloride (DMA), chlorpromazine (CH), and dynasore, which target lipid raft, macropinocytosis, clathrin-dependent endocytosis and dynamin-dependent or independent endocytosis, respectively. To assess the impact of the inhibitors on MkMP uptake, we compared the outcomes from the inhibitor studies against the uptake of the following molecules (positive controls), cholera toxin subunit B (CT-B), dextran 10k (Dx), and transferrin (Tf), which are established to be taken up by lipid-raft mediated endocytosis, macropinocytosis, and clathrin-dependent endocytosis, respectively. Specifically, d3-HSPCs were pre-incubated with or without 5 mM MβCD, 10 µM DMA, 20 µM CH, or 80 µM dynasore for 45 min at 37 °C, before the coculture with (A–D) CFDA-SE-stained MkMP for 30 min, (B) CT-B, (C) Dx, or (D) Tf for 15 min at 37 °C. Uptake of MkMP, CT-B, Dx, or Tf were analyzed by flow cytometry. Data represent averages of 3 biological replicates ± standard error of mean. *, P<0.05; **, P<0.01; ***, P<0.001