4 The epithelial–mesenchymal transition (EMT) marker expression regulation in modulated YKL-40 gene expression NSCLC. a EMT markers expression analysis of YKL-40 overexpressed CL1-1 cell (I) and YKL-40 reknockdown of YKL-40 overexpressed CL1-1 cell, as well as b EMT markers expression analysis of YKL-40 knockdowned CL1-5 cell (I) and YKL-40 re-overexpression of YKL-40 knockdowned CL1-1 cell using RT-PCR and Western Blot analysis.