Transient transfection of individual Sp100 isoforms suggested that only Sp100A localized in both the nucleus and cytosol (Fig. S1G), and scrutiny of various human normal and cancer cell lines indicated a ubiquitous presence of cytosolic Sp100, matching the electrophoretic mobility of Sp100A in denatured polyacrylamide gels (Fig. S1H). The gene discussed is SP100; the disease is cancer.