Cross talks between signaling pathways downstream of PRRs. (a) Cross talk between different TLRs. The diagram illustrates the cross talks between TLR3 and TLR 7-9, and between TLR4 and TLR7-9. For instance, TLR4 (in pink) and TLR7-9 (in yellow, light purple, and blue, respectively) signaling pathways converge at both IKKs and MAPKs. (b) Cross talk between TLR3 and RLRs (RIG-I and MDA5). (c) Cross talk between TLR4 and NLRs (NOD1 and NOD2). (d) Cross talks between TLRs and CLRs. The diagram illustrates the cross talks between TLR2 and Dectin-1, and between TLR4 and Dectin-1. Symbols: black or color-coded filled arrows, stimulatory reactions; black dashed and double-dotted lines, transcriptional activation reactions; black filled arrows with a bar, transport reactions. The presence of two forward slashes signifies that known stimulatory reactions (i.e. intermediate reactions) were omitted. PRR entities that are bordered with a dotted frame are considered in an active state.