Although definitive identification of MSCs in vivo ischallenging, reduced numbers of Stro-1-positive cells and expression of p16 in apredominantly nuclear distribution within spindle-shaped, vimentin-positive cells inhypocellular areas support the hypothesis that stromal support for haematopoiesis isimpaired in MS-patient marrow. The gene discussed is VIM; the disease is myeloid sarcoma.