Sir

I would like to clarify my earlier Correspondence (“Patent dispute hangs over kringle 5”, Nature 407, 128; 2000) about a patent dispute over an angiogenesis inhibitor involving my laboratory and Abbott laboratories.

My laboratory did not contact Miguel Llinás of Carnegie-Mellon University about supplying kringle-containing plasminogen fragments until some months after our angiostatin paper appeared (Cell 79, 315–328; 1994) in October 1994.

Llinás and Johann Schaller of the University of Bern, who have done pioneering work on the biophysical and functional characteristics of the kringle domains of plasminogen, subsequently were very helpful in supplying samples of fragments from human plasminogen to Yihai Cao in my laboratory.

Cao later published two papers on his results, including Llinás and Schaller as authors because of their help in supplying plasminogen fragments and advice.