UCSF researchers published that the oncogene Src, long considered an intracellular kinase, appears on the extracellular membrane of multiple tumor types via autophagolysosomal exocytosis and can be targeted by antibody‑based therapies (Science). In mouse models, antibodies directed at extracellular Src (eSrc) delivered radioactive payloads or recruited immune effectors and produced tumor regression. The team proposes eSrc as a broadly applicable cancer antigen present in many solid tumors and demonstrated proof‑of‑concept for antibody‑drug conjugates and immune‑recruiting formats. Surface exposure of traditionally intracellular oncoproteins creates new target space for antibody therapeutics; further validation in human tissues and safety profiling will be required to move toward clinical translation.