The SMAL web server: global multiple network alignment from pairwise alignments

Alignments of protein-protein interaction networks (PPIN) can be used to predict protein function, study conserved aspects of the interactome, and to establish evolutionary correspondences. Within this problem context, determining multiple network alignments (MNA) is a significant challenge that involves high computational complexity. A limited number of public MNA implementations are available currently and the majority of the pairwise network alignment (PNA) algorithms do not have MNA counterparts. Furthermore, current MNA algorithms do not allow choosing a specific PPIN relative to which an MNA could be constructed. Also, once an MNA is obtained, it cannot easily be modified, such as through addition of a new network, without expensive re-computation of the entire MNA.