In 2005, he joined CNIO to lead the Genomic Instability Group where he has been ever since. Initial works from the lab concentrated on exploring the role of replicative stress in cancer and ageing, for which the group combined cell biology, mouse models and drug development projects. Among other discoveries, the group developed inhibitors of the ATR kinase and showed their potential for cancer therapy. These compounds were later licensed to the pharmaceutical industry for clinical development. Today, several companies have ATR inhibitors at various stages of clinical development, which to a significant extent was influenced by early works from the laboratory. More recently, the group has expanded to other areas such as mechanisms of drug resistance and neurodegenerative diseases.