We sought to determine if the major WT1 isoforms overexpressed in leukemias and multiple solid tumors, which occur as a result of alternative splicing at Exon 5 and Exon 9 (WT1 isoforms A [EX5-/KTS-], B [EX5+/KTS-], C [EX5-/KTS+] and D [EX5+/KTS+] [24] are also overexpressed in primary KS lesions. The gene discussed is WT1; the disease is leukemia.