TLR3 and dry eye syndrome: Our finding that basal KCs strongly express TLR3 and PKR, and modestly express RIG-I and MDA5 protein, suggests that the primary reactions triggered by p(I:C) in vivo are most probably mediated by TLR3 and PKR, while RIG-I and/or MDA5 might contribute to the amplification of dsRNA-signaling KCs.