The exact function of MAP2 is unknown but MAPs may stabilize the microtubules against depolymerization. They also seem to have a stiffening effect on microtubules.
DeGiorgis J.A., Jaffe H., Moreira J.E., Carlotti C.G. Jr. Proteome Res. 4:306-315(2005)
Olsen J.V., Blagoev B., Gnad F., Macek B. Mann M.Cell 127:635-648(2006)
Matsuoka S., Ballif B.A., Smogorzewska A., McDonald E.R. Science 316:1160-1166(2007)