TIMP-1 effect on transcription regulators. (A) Immunohistochemistry showing down-regulation in TIMP-1JD38 tumor of the Tfs BCL-6 and PAX-5 and increasing expression of MUM-1/IRF-4; original magnification × 400. LXSN-JD38 and TIMP-1JD38 xenotransplants express XBP-1; original magnification × 400. (B) Western blot showing equal ratios of XBP-1 active/inactive forms by JD38 control cells and TIMP-1JD38 cells as compared with multiple myeloma cell lines (1, 2, and 3) in which the XBP-1 active form is up-regulated. (C) Western blot analysis confirms STAT-1 and STAT-3 up-regulation by TIMP-1 and demonstrates phosphotyrosine-activated STAT-3 and not STAT-1 in TIMP-1JD38 cells. Equal protein loading was monitored by β-actin Western blot.