Background: SMG1 is a PIKK (phosphoinositide 3-kinase related kinases) protein kinase that plays a key role in RNA surveillance via nonsense-mediated mRNA decay (NMD). SMG1 phosphorylates Upf1, a factor that possesses RNA helicase activity and is also central to NMD. SMG1 and UPF-1 have been shown to exist in a complex with the translation termination release factors eRF3, and eRF1. This complex has been termed SURF and associates with the exon junction complex (EJC) to function in the recognition of premature termination codons in aberrant RNAs to trigger NMD.