Axl knockdown in KS cells inhibited cell growth and invasion. (A) The 293T, KS-SLK, KS-IMM, LTC, and A549 cells were transfected with Axl siRNA or control siRNA (50nM) for 72 hours. Cell numbers were determined at the end of the experiment with the MTT method. (B) Apoptosis of LTC cells 72 hours after 50nM siRNA transfection was analyzed with TUNEL assay (green). Nuclei were counterstained with DAPI. Apoptosis was significantly increased in Axl siRNA-transfected cells. Images were taken with an Olympus AX70 fluorescence microscope (20× objective) and Spot Version 2.2.2 digital imaging system. (C-E) Effect of Axl knockdown on the invasion of HUVEC (C), LTC (D), and KS-IMM (E) was analyzed by transwell invasion assay. The experiment was performed in triplicate. The cells that accomplished invasion were counted in 10 individual high-powered fields for each membrane under a light microscope, and the numbers were shown below each representative picture.