The microtubule stabilizer paclitaxel and MT-destabilizing vinorelbine were shown previously to inhibit both constitutive and cytokine-induced tyrosine phosphorylation of STAT3 with a concomitant increase in the extent of its constitutive serine phosphorylation in human breast, ovarian and prostate cancer cell lines [29,30]. Here, STAT3 is linked to prostate carcinoma.