This review discusses these new topics: a brief introduction of okadaic acid class compounds; isolation and characterization of PP2A inhibitors, SET and CIP2A; progression of leukemia, breast and lung cancers with SET; anticancer effects of SET antagonists; and finally, TNF-α-inducing protein (Tipα) of Helicobacter pylori (H. pylori). Here, CIP2A is linked to lung cancer.