Mesothelin was originally identified as megakaryocyte potentiating factor (MPF), and later termed mesothelin when it was shown that an antibody against it reacted with ovarian cancers and malignant melanomas [15], [16] and as early as 1999 it was shown that mesothelin related peptides could be detected in the serum of ovarian cancer patients [17]. The gene discussed is MSLN; the disease is ovarian cancer.