Complement activation contributes to tumor progression in several cancer types. In this issue, Daugan and colleagues propose complement component C1s and C4d as new markers of prognosis in clear cell renal cell carcinoma. The mechanism of action of C1s involves both canonical and intracellular, noncanonical functions. The results provide new molecular targets to prevent tumor escape from immune surveillance, which leads to tumor progression.
See related article by Daugan et al., p. 891 (2).