In the article by T. L. Frandsen et al., entitled “Direct Evidence of the Importance of Stromal Urokinase Plasminogen Activator (uPA) in the Growth of an Experimental Human Breast Cancer Using a Combined uPA Gene-Disrupted and Immunodeficient Xenograft Model,” which appeared in the January 15, 2001 issue of Cancer Research (pp. 532–537), the equation on page 534 appeared incorrectly as:

The correct equation appears below.

Thomas Leth Frandsen

Claus Holst-Hansen

Boye Schnack Nielsen

Ib Jarle Christensen

Jens R. Nyengaard

Peter Carmeliet

Nils Brünner