A pyridine hydrazone that broadly inhibits Jumonji histone demethylases (IC50 values are 230, 340, 435, 445, 855, and 1100 nM for JARID1A, JMJD2E, JMJD2B, JMJD2A, JMJD3 and JMJD2C, respectively); inhibits Jumonji demethylase activity, alters gene expression, and blocks viability of cancer cells both in vitro and in vivo