Production of an active urokinase by leukemia cells: a novel distinction from cell lines of solid tumors.

A new screening test is described which enabled rapid determination of the proportion of single-chain and two-chain urokinase produced in the culture supernatants of 18 human cell lines. A clear distinction was found between two groups of cell lines: cells derived from ten solid tumors produced almost exclusively single-chain proenzyme, while the majority of the enzyme found in cultures of eight leukemia cell lines was in the active, two-chain form.