Two proteins on the surface of the liver cell, called CD81 and SR-B1, are used by the parasites to invade the cell. However, parasite species differ in which of the pathways they can use. P. falciparum (yellow) and P. yoelii (red) interact with CD81 to enter the liver cell, P. vivax (green) interacts with SR-B1, and P. berghei (blue) can use either protein. Two proteins called P52 and P36 on the surface of the parasite were thought to play roles in the cell invasion process. Manzoni et al. found that the P36 protein on the surface of P. berghei holds the key to the ability of this parasite species to use the SR-B1 pathway. Replacing the P36 protein on P. berghei with the P36 protein from P. yoelii (PyP36) meant that the parasite could now only enter the liver cell via the CD81 pathway (as shown second from right). Conversely, replacing the P36 protein on P. yoelii with the P36 protein from P. berghei (PbP36) enabled this parasite species to use either CD81 or SR-B1 to enter liver cells (as shown far right). It remains to be seen whether P36 and SR-B1 interact directly. SR-B1: Scavenger Receptor B1.