Interestingly, formononetin was found to inhibit the constitutive activation of the signal transducer and transcriptional activator 3 (STAT3) (tyrosine residues 705 and 727) and STAT5 (tyrosine residues 694 and 699) in multiple myeloma cells, which was associated with the suppression of upstream kinases. This evidence concerns the gene STAT3 and plasma cell myeloma.