This motif is found at the C-terminus of proteins that are related to the EB1 protein. The EB1 proteins contain an N-terminal CH domain pfam00307. The human EB1 protein was originally discovered as a protein interacting with the C-terminus of the APC protein. This interaction is often disrupted in colon cancer, due to deletions affecting the APC C-terminus. Several EB1 orthologues are also included in this family. The interaction between EB1 and APC has been shown to have a potent synergistic effect on microtubule polymerization. Neither of EB1 or APC alone has this effect. It is thought that EB1 targets APC to the + ends of microtubules, where APC promotes microtubule polymerization. This process is regulated by APC phosphorylation by Cdc2, which disrupts APC-EB1 binding. Human EB1 protein can functionally substitute for the yeast EB1 homolog Mal3. In addition, Mal3 can substitute for human EB1 in promoting microtubule polymerization with APC.