In "This Month in Nature Biotechnology" (Nat. Biotechnol. 17, 214, March 1999 ), a brief describing a research article on directed DNA evolution of thymidine kinase incorrectly stated that the viral form of the enzyme has lower substrate affinity than the human form. The viral form actually has lower substrate specificity.

In the February 1999 issue of Nature Biotechnology, a chart listing recent IPOs gave the incorrect location for Centaur Pharmaceuticals. Centaur Pharmaceuticals is based in Sunnyvale, CA, and is not affiliated with Centaur, Inc. of Overland Park, KS.

Several reference errors occurred in a recent commentary by Richard C. Strohman (Nat. Biotechnol. 17, 112 , February 1999). In the text (para. 4), ref. 8 should be ref. 9; (para. 6) ref. 4 should be ref. 9; (final para.) refs 9–12 should be refs 10–13, respectively. Changes to the listed references 2 and 8, and an additional ref. 13 are printed below:

2. Kauffman,S.A. J. Theor. Biol. 22, 437–467 (1969);Kauffman,S.A. The origins of order (Oxford Univ. Press, New York, 1993);Thomas, R.Int. J. Dev. Biol. 42, 479–485 ( 1998); Thieffry, D. et al. BioEssays 20, 433–440 ( 1998).

8. Wahlsten D. Ann. Rev. Psychol. 50, 599–624 (1999).

13. Rubin, H. J. Surg. Oncol. 69, 4–8 (1998); Walliszewski, P. et al. J. Surg. Oncol. 68,70– 78 (1998).