Depletion of CD44 in human Kras-mediated lung adenocarcinoma cells inhibits MAPK activation and cell proliferation. (a) Immunoblot analysis of CD44 (antibody from R&D, Minneapolis, MN, USA) in H358 cells expressing control or CD44 shRNAs. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH, antibody from Millipore, Billerica, MA, USA) serves as a loading control. (b) Immunoblot analysis of phospho-Erk (antibody from Cell Signaling, Danvers, MA, USA) in control and CD44 shRNA-expressing H358 cells. Cells were serum starved and then stimulated with EGF (0.5 ng/ml) at different time intervals as indicated. b-Actin (antibody from Sigma-Aldrich, St Louis, MO, USA) serves as a loading control. (c) Cell proliferation assay of H358 cells that express control or CD44 shRNAs.