Fig. 3.

a and b CL1-1 cells (I) were transfected with the green fluorescent protein (GFP) expression plasmid (pEGFP-C1) plasmid, encoding empty vector (II) or full-length YKL-40 (III). After stable expression, cells were knockdowned via shRNA against human YKL-40 (IV). Four cells were subjected to Matrigel invasion assay (a) and transwell migration assay (b). c and d CL1-5 cells (I) were transfected with shRNA vector control (II) or shRNA against human YKL-40 (III). The cells were then co-transfected with the DsRed plasmid encoding YKL-40 (IV). The ability of these four cells to invade through Matrigel (c) or to migrate (d) was assayed. Mean ± transwell assay was determined by three independent experiments; statistical significance was measured using one way ANOVA, *, P < 0.05, **, P < 0.01, ***, P < 0.001. e in vivo study of each transfected cell lines’ migration ability. Each transfected cell lines were injected into nude mice for 6 weeks before lung harvest and lung nodules number determination. This experiment was conducted in triplicates for each group