Even within a single patient with cancer, there is a vast diversity of individual tumor cells, which display distinct behaviors related to growth, metastasis, and responses to chemotherapy. To carry out these behaviors, each cancer cell uses its genes to make the needed molecules in a unique way known as its “gene expression signature.” To correlate gene expression signatures with cancer progression and chemotherapy resistance, a team of scientists led by Rong Lu from USC and Akil A. Merchant from Cedars-Sinai have introduced a new genetic technology in a study published in Nature Communications.