Michael R. Lieber is a professor at the Keck School of Medicine of the University of Southern California, where he holds the Rita Edward Polusky Chair in Basic Cancer Research. His research interests primarily focus on the molecular mechanisms underlying DNA double-strand breaks in the immune system, particularly involving V(D)J recombination and nonhomologous end joining pathways that are critical for immune repertoire and lymphocyte development. Lieber's laboratory investigates how deficiencies in these pathways can lead to severe combined immune deficiency (SCID) and contribute to cancer through chromosomal translocations and genomic instability. With a strong emphasis on the molecular biochemistry of DNA repair proteins, his work has identified key enzymes and complexes such as DNA-PKcs and Artemis that play vital roles in these processes. Lieber has contributed significantly to the understanding of how structural variations in DNA lead to oncogenic events and aims to develop therapeutic strategies targeting these pathways to improve cancer treatment.