a Immunoprecipitation using the lysates of A549 cells showing the interaction between PTPL1 and p38 MAPK. b Control and PTPL1 knockdown A549 cells were treated with TGF-β1 and/or SB203580, and were subject to Transwell assay for cell invasion (each bar represents the mean ± SEM. **P < 0.01, ***P < 0.001, ****P < 0.0001. ns, non-significant). c–e Control and PTPL1 knockdown A549 cells were treated with TGF-β1 and/or SB203580. The morphological changes of the cells were observed by microscope (c), and the changes of EMT-related proteins were analyzed by Western blot (d, e) (each bar represents the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. ns, non-significant). f Schematic diagram for PTPL1 regulation of TGF-β signaling in EMT of NSCLC cells.