 When CD99 expression is knocked down in human cells with Ewing's sarcoma and those cells are grafted onto mice, tumor and bone metastasis development is reduced.Reducing CD99 expression results in higher β-III tubulin expression and more neurite outgrowth.Upregulating CD99 expression in the cell line L428, a Hodgkin's lymphoma line, resulted in those cells redifferentiating towards B cells.