Knockdown of MKL1 in HL-60 neutrophil-like cells mimics patient phenotype. HL-60 cells were differentiated into neutrophil-like cells for 5 days in culture media containing 1.3% dimethylsulfoxide. (A) Western blot of the MKL1 expression levels in undifferentiated (HL-60) or differentiated (dHL-60) cells carrying SCR or the shRNA against MKL1 (MKL1). (B) Migration of SCR and MKL1 neutrophils in a Dunn chamber in response to an fMLP gradient. Tracks show migration path over time. Scale bar = 20 μm. (C) Frequency distribution of the velocity of dHL-60 SCR and MKL1 cells during migration in a Dunn chamber in response to fMLP. The number of cells analyzed was 115 for SCR and 156 for MKL1 cells in 3 independent experiments. (D) Chemotactic index of dHL-60 SCR and dHL-60 MKL1 cells during migration in a Dunn chamber. (E) Instant angle distribution during the migration of SCR and MKL1 dHL-60 cells. ***P < .001.