Fig. 3

TGFβ induces an EMT-associated kinase switch that promotes erlotinib resistance of CD166⁺ OSCs. a Tumor cell supernatants of CD166⁺ and CD166⁻ cells from OS-1 or OS-5 were collected and differential levels of TGFβ production were analyzed by ELISA. Note: Columns, mean of three individual experiments; SD,** P < 0.01. b Immunoblot analysis was performed with antibodies against phosphorylated and total AKT, EGFR and Vimentin, E-Cadherin. GAPDH was used as the control. c With the presence of erlotinib, cell viability of CD166⁻ cells with or without the treatment of TGFβ1 were determined by MTT. Note: Columns, mean of three individual experiments; SD,** P < 0.01. d Phase-contrast images of the ability of tumor spheres formation by seeding with CD166⁻ cells with or without the treatment of TGFβ1 in serum-free medium. Scale bar, 50 μm. e Flow cytometry analysis of CD133 in CD166⁻ cells (from OS-1) without the treatment of TGFβ1