FIGURE 9. Schematics showing the function of MFN2 in HL60 adhesion.

(A) During the neutrophil-directed differentiation of HL60 cells, β₂ integrin activation increases in response to fMLP stimulation, which is critical for cell adhesion. We call this process the maturation of β₂ integrin activation. Expression of β₂ integrins, fMLP receptor FPR1, CD87, and CD35 also increase during the neutrophil-directed differentiation of HL60 cells. The maturation of β₂ integrin activation is associated with the expression of β₂ integrins, CD87, and CD35. Thus, the expression of β₂ integrins, CD87, and CD35 can serve as markers for the maturation of β₂ integrin activation. (B) Knockdown of MFN2 inhibited the maturation of β₂ integrin activation during the neutrophil-directed differentiation of HL60 cells, causing less expression of FPR1, CD87, and CD35, less activation of β₂ integrins, and less cell adhesion underflow. (C) In β₂ integrin activation matured cells (CD87^high in this study), the loss of MFN2 expression decreases β₂ integrin