The current trend in innovative cancer therapy is moving towards targeting the genes of interest by means of oligonucleotides developed for therapeutic or diagnostic use. These new approaches are of particular interest in oncology, and it would therefore be extremely useful to characterise all the biological tools currently available in this field. The chemoresistance profiles of four human cancer cell lines were determined by identifying of the operating conditions needed to characterise the presence of hmdr1, mrp and lrp mRNA by gene amplification.