There exists evidence that DDAH2 expression may be up or down regulated in different tumor types, as exemplified by ovarian carcinoma and oral squamous cell carcinoma respectively.[69, 70] High levels of proteins HSP90b1 and αB-crystallin are typically associated with cancer progression.[62, 71–73] Surprisingly, these proteins were found to be significantly more highly expressed in thymoma A over thymoma B3, despite B3 being the more severe disease. Here, DDAH2 is linked to thymoma.