E1841K mutant decreases the number of cAMP-induced formation of actin framework around WPBs due to decreased phosphorylation of NMII-A at S1916. (A) Western blotting of p-S1916 and total NMII-A in HUVECs expressing flag-tagged NMII-A WT and 5 MYH9-RD mutants stimulated with forskolin for 15 minutes. (B) Immunostaining of VWF (yellow), flag (magenta), and F-actin (cyan) in HUVECs expressing flag-tagged NMII-A WT and 5 MYH9-RD mutants. Scale bars represent 2 μm. (C) Quantitative analysis of the number of actin framework-coupled WPBs per cell. (D) The total number of WPBs per cell (n = 16; NS > 0.05; **P < .01). NS, not significant.