TLR4 and infection: Drosophila Toll protein (TLR4) is a representative receptor for Gram-negative LPS of Gram-negative bacteria, which is a critical bridge molecule linking oncogenic infections to cancer.[5] As a vital member of the TLRs family, TLR4 has an extracellular structural domain composed of 22 leucine-rich repeat sequences, which can be expressed in some cells.[20] Upon activation by LPS, LBP translocates to and binds to the TLR4/MD-2 complex via CD14.