I study two protein isoforms of WNT5A that differ from one another by only 18 amino acids post-processing. These isoforms are highly conserved among vertebrates. We see no evidence that these isoforms are functionally distinct from one another. With every assay I do, it looks more and more like the isoforms are completely redundant.
Assuming that these isoforms are functionally redundant, what could possibly be driving them to be so highly conserved?