STAT3 and cancer: Ma et al. investigated the anti-cancer effect and underlying mechanisms of Proscillaridin A (PSD-A), a cardiac glycoside component of Urginea maritima. They found that PSD-A was able to inhibit both constitutive and inducible STAT3 activations and reduce STAT3–DNA binding activity, which was associated with increased expression of SH2 domain-containing protein tyrosine phosphatase 1 (SHP-1), decreased phosphorylation of Src, and binding of PSD-A with the STAT3 SH2 domain.