Purification of antineoplastic factor from eggs of a sea hare

An antineoplastic factor inducing tumor lysis was purified to apparent homogeneity from the supernatant of a homogenate of eggs of the sea hare Aplysia kurodai. On gel filtration, the purified substance gave a single band of material of 250 kDa containing 3 different subunits and this band coincided with cytolytic activity. The purified factor was half-maximally active at 10-60 ng protein/ml and lysed all tumor cells tested, but not normal cells.