For example, hypoxia did not affect the expression of RhoB in renal carcinoma Caki‐1 cells 23 and in U87 glioblastoma cells 24; but hypoxia did up‐regulate the expression and activation of RhoB in human pulmonary artery endothelial and smooth muscle cells, in which RhoB is involved in the regulation of pulmonary vascular tone and structure, and promotes development of pulmonary hypertension 15. Here, RHOB is linked to pulmonary arterial hypertension.