In vitro (A-B) properties of shRNA clones (clone-1 and -3) compared to scrambled control: (A) mRNA expression by reverse-transcription PCR relative to standard, (B) invasion assay using co-cultures with cancer-associated fibroblasts (CAF) and mitomycin C to block tumor cell proliferation. In vitro CXCR2 inhibition with CXCR2-antagonist (C, D): invasion assay using co-cultures of 344P (C) and 344SQ (D) cell lines treated with increasing concentrations of SB225002.In vivo properties of shRNA clones (clone-1 and -3) compared to scrambled control (E, F): number of left lung tumor nodules, (E) number of distant metastases (F). Median and inter-quartile range are shown in the dot plots (E, F). Wilcoxon rank sum test (A, B, E, and F) between scrambled control and shRNA single clones (clone-1 and clone-3) or between different concentrations of SB225002and the control (C, D).