The recognition of molecular mechanisms involved in drug resistance may improve basic knowledge of signalling pathways involved in resistance to anticancer drugs and also improve outcomes in patients with drug-resistant cancers that have poor prognosis, such as triple negative breast cancer (TNBC) and metastatic melanoma. Integrins are cell surface molecules that mediate sensitivity to anticancer drugs, migration and invasion, and therefore represent a suitable target for therapy. This proposal investigates the molecular mechanism behind knockdown of integrins alpha v beta 3, alpha v beta 5, alpha v beta 6, alpha 3 beta 1, alpha 4 beta 1 and alpha 5 beta 1 using integrin subunit specific siRNAs (beta 3, beta 5, beta 6, alpha v, alpha 3, alpha 4 or alpha 5) and the ability of such a treatment to sensitise TNBC and melanoma cell lines to anticancer drugs paclitaxel, vincristine and cisplatin. Our next goal is to identify how specific integrin knockdown influences cell migration and invasion. The focal adhesions (FA) are sites of attachment between cells and extracellular matrix which may mediate differential cell responses by variation of FA protein composition. Therefore, the FA protein composition will be investigated before and upon integrin silencing using proteomics methodology. We will monitor formation and temporal evolution of FA in living cells during spreading or migration using reflection interference contrast microscopy (RICM). On the basis of these data, several signalling pathways will be proposed and their involvement in sensitivity to anticancer drugs, migration and invasion will be experimentally verified. Our data will contribute to the knowledge on integrin signalling pathways, structure and function of focal adhesions. The understanding of integrin pathways involved in sensitivity to anticancer drugs, migration and invasion processes may provide novel insights into biology of these cancer cells and identify new target molecules in TNBC or melanoma.