The fact that we observe NPM-ALK–expressing tumor cells that show a surface marker expression pattern that is typical for DN cells, as well as the presence of immature single positive cells suggests, that an immature thymic cell population is targeted for transformation or that a more mature cell population regresses to a progenitor stage during transformation, potentially through direct repression of the T-cell phenotype by the ALK oncogene (46). The gene discussed is ALK; the disease is neoplasm.