Potential inhibitors of bortezomib (Bort)-induced Sp downregulations in MM, colon, and pancreatic cancer cells. ANBL-6 and RPMI 8226 cells (A) and L3.6pL and SW480 cells (B) were treated with bortezomib alone or in combination with Z-FA-FMK, FMK-ZEITD, or OKA for 24 hours, and whole-cell lysates were analyzed by Western blots. Treatment with the inhibitors alone (Z-FA-FMK, FMK-ZEITD, or OKA) did not affect Sp expression (data not shown). ANBL-6 and RPMI 8226 (C) and L3.6pL and SW480 (D) cells were also treated with bortezomib alone or in combination with DVED, and whole-cell lysates were analyzed by Western blots. ANBL-6 and RPMI 8226 cells (E) and L3.6pL and SW480 cells (F) were treated with bortezomib alone or in combination with antioxidants, and whole-cell lysates were analyzed by Western blots.