Fig 1. CXCR4 expression in human lung cancer cells and its inhibition by IL-24.

A, Endogenous CXCR4 and AKT protein expression in human lung cancer cell lines. B, IL-24 reduced CXCR4 expression at 24 h and 48 h in doxycycline-treated H1299-IL24 cells but not in doxycycline untreated control cells. C, IL-24 reduced GRK6, phosphorylated (p) CXCR4 and total CXCR4 expression in doxycycline-treated H1299-IL24 cells compared to expression of these proteins in doxycycline untreated H1299-IL24 cells. D, Immunocytochemistry showing doxycycline-induced IL-24 expression in H1299-IL24 cell line reduced CXCR4 expression. Cells that were not treated with doxycycline served as control. Magnification IL-24- X 30; CXCR4- X 40. E, Time-course study showed CXCR4 expression was reduced as early as 4 h after IL-24 expression and the inhibitory activity was sustained up to 24 h in doxycycline-treated H1299-IL24 cells. Beta actin was used as protein loading control in Western blotting assays.