[i] The IAPs and IAP-agonists (Smac; HtrA2; XAF) of humans and mice are compared. The murine cDNAs found exclusively in the RIKEN database are indicated. (N/A) Not applicable, indicating the data was already present at NCBI. In mice, approximately six NAIP genes have been identified in a cluster on chromosome 13. At least three of these are transcriptionally active and likely to encode functional proteins (Huang et al. 1999; Endrizzi et al. 2000)