Phylogenetic tree analysis of DExD/H box RNA helicases. Multiple alignment of the full length protein sequences of known or predicted RIG-I, MDA5, LGP2, eIF4A and DICER was generated by CLUSTALW http:///www.ebi.ac.uk and used for construction of a phylogenetic tree using the neighbour-joining method within the Mega3.1 programme. The bootstrap values of the branches were obtained by testing the tree 10,000 times and values over 50% percent marked. The sequences used for tree construction are listed in Table 1. Others are as follows: monkey MDA5, NP_001040588; mouse MDA5, EDL26991; pig_MDA5, NP_001093664; mouse LGP2, NP_084426; cow LGP2, NP_001015545; dog LGP2, XP_860567; mouse RIG-I, Q6Q899; pig RIG-I, Q9GLV6; mouse DICER1, EDL18787.