Cell shape and cytoskeleton micromechanics are altered by Smad protein phosphorylation in the bone marrow embryology via RhoA/ROCK‐mediated tension generated by BMP‐induced signalling.[46] Other groups have looked at the essential interplay between biochemical and mechanical cues in cell differentiation and as micromechanics plays key roles in both the normal physiology and embryology.[47] Our hypothesis was that mechanical stress might modulate the progression of primary myelofibrosis by targeting TGF‐β pathways in the bone marrow microenvironment. Here, RHOA is linked to myelofibrosis.