The mouse Nell1 cDNA and amino acid sequences are disclosed. Also disclosed is a Nell1 knock-out mouse with several bone- and cartilage-related defects. On the molecular level, the loss of Nell1 function led to reduced expression of certain extracellular matrix proteins. The disclosure here provides new tools for studying bone and cartilage development as well as new drug screening and treatment strategies for bone- and cartilage-related diseases and conditions.
STATEMENT REGARDING GOVERNMENT LICENSE RIGHTS
 The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of contract Nos. DE-AC05-000R22725 and KP1104010 awarded by U.S. Department of Energy.