A cytolytic factor inducing tumor lysis was purified approx. 1000-fold from purple fluid of the sea hare Aplysia kurodai. The purified factor appeared homogeneous on polyacrylamide gel electrophoresis and consisted of a single polypeptide chain of 60 kDa. The cytolytic factor was half-maximally active at 3–25 ng protein/ml and lysed all tumor cells tested, but not normal cells.
