This research described in thesis was undertaken in an attempt to increase our knowledge of mechanisms by which lung cancer cells acquire the capacity to invade This is a critical step in cancer metastasis. To study the molecular nature of invasion, the gene-expression profiles of five lung cancer cell lines (DLKP) with differing levels of mvasiveness (as determined by an in vitro invasion assay) were analysed using expression microarray methodology. Two invasive, non-drug exposed, variants of the DLKP cell line were used in the study along with a non-invasive Vincnstine-selected (VCR) cell line, an invasive Taxotere (TXT) resistant variant and a non-mvasive TXTselected cell line that had lost its resistance to TXT. This provided us with a panel of lung cancer cell lines with various levels of mvasiveness Lists were generated from the array data contaimng genes that may potentially serve as transcriptional signatures for mvasiveness and/or drug resistance in these cell lines From the genelists compiled, and taking into account results from PCR-based validation and evidence from existing literature, five genes were picked as high priority targets for further investigation in the context of our invasion model. These were IGF-1R, KCNJ8, S100A13, SFN, and TFPI2. Functional studies to investigate the role of these targets in invasion included gene over-expression and knockdown using cDNA and siRNA transfection respectively, with confirmation by semi-quantitative RT-PCR, qRT-PCR and Western blotting where possible. Most importantly any functional effect in our cell model was examined by in vitro invasion assay. The functional analyses identified a role for IGF- 1R and TFPI2 in the invasive phenotype and also identified novel roles for the proteins KCNJ8 and S100A13 in invasion.