The present invention relates to the roles played by the JARID1B genes in cancers and features a method for treating cancers by administering a composition comprising a double-stranded molecule against the JARID1B genes or a vector encoding them. The present invention also features methods for diagnosing cancers by detecting the expression of JARID1B. To that end, JARID1B serves as a serological biomarker for cancers. Also, disclosed are methods of identifying candidate agents for treating or preventing cancer or inhibiting cancer cell growth, using the expression of JARID1B in the cancer cells or the cell proliferation resulted from expression of JARID1B as an index.
