STAT3 and plasma cell myeloma: We recently compared the sensitivity and specificity of AG490 to those of a novel pan-Jak inhibitor (P6) on IL-6-dependent myeloma cells and determined that P6 inhibited Jak/Stat3 signaling with higher sensitivity and specificity than those of AG490, which indiscriminately inhibited growth of cell lines, even those lacking activated Jaks and Stats [35-37].