The goal of the Mammalian Gene Collection (MGC), a trans-NIH initiative, is to provide full-length open reading frame (FL-ORF) clones for human, mouse, and rat genes. In 2005, the project added the cow cDNAs generated by Genome Canada. Initially, cDNA libraries provided the source of the clones. Recently, alternative methods based on gene-specific amplification have been developed to target the recovery of human and mouse genes absent from the MGC collection.