Likewise, since CD31 negativity rules out that putative CD34+SCs/TCs are not ECs, the use of double staining with CD34 and SMA is an especially useful and very affordable procedure for following the perivascular cell changes associated with angiogenesis, as well as the presence or not of myofibroblasts and their perivascular source during repair, fibrosis, and tumor stroma formation. The gene discussed is CD34; the disease is neoplasm.