In that JAKs play an essential role in driving oncogenic Stat3 signalling (De Vos et al, 2000; Ni et al, 2000; Zhang et al, 2000; Li and Shaw, 2002; Rane and Reddy, 2002), the ability of 15d-PGJ2 to downmodulate IL-6/JAK signalling may also in part, explain the antineoplastic properties of this agent against other types of human cancer. Here, STAT3 is linked to cancer.