The invention relates to a set of isolated marker genes comprising at least one gene identified as having differential expression as between patients wh o are responders and non responders to an erbB receptor tyrosine kinase inhibitor; said gene set comprising one or more genes selected from at least the group consisting of the (51) genes listed herein including gene-specific oligonucleotides derived from said genes; and uses of sauch sets in diagnost ic applications.
