However, in 1991 (prior to the discovery of TIL) it was observed that a molecule with a clear role in immune function in mammals, the interleukin-1 (IL-1) receptor, also had homology to drosophila toll; the cytoplasmic portions of both molecules were similar.
Porén, en 1991 (antes do descubrimento do TIL) observouse que unha molécula cunha clara función inmunitaria nos mamíferos, o receptor da interleucina-1 (IL-1), tamén tiña homoloxía co Toll de drosófila, xa que as porcións citoplasmáticas de ambas as moléculas eran similares.