ACTA1 and cancer: After morphological examination, key morphological elements were identified that indicated a change in the state of a hematological niche: the number of active cells on the endost, the density of microcirculation vessels, the expression of the CXCR4 protein (a prognostic marker for MM), the detection of cells, positively stained with an antibody against alpha smooth muscle actin (αSMA+, a marker of TME MSC and cancer-associated fibroblasts, CAF).