Besides the classic MAP groups, novel MAPs have been identified that bind the length of the microtubules. These include STOP (also known as MAP6), and ensconsin (also known as MAP7).
In addition, plus end tracking proteins, which bind to the very tip of growing microtubules, have also been identified. These include EB1, EB2, EB3, p150Glued, Dynamitin, Lis1, CLIP170, CLIP115, CLASP1, and CLASP2.
Another MAP whose function has been investigated during cell division is known as XMAP215 (the "X" stands for Xenopus). XMAP215 has generally been linked to microtubule stabilization. During mitosis the dynamic instability of microtubules has been observed to rise approximately tenfold. This is partly due to phosphorylation of XMAP215, which makes catastrophes (rapid depolymerization of microtubules) more likely. In this way the phosphorylation of MAPs plays a role in mitosis.
There are many other proteins which affect microtubule behavior, such as catastrophin, which destabilizes microtubules, katanin, which severs them, and a number of motor proteins that transport vesicles along them. Certain motor proteins were originally designated as MAPs before it was found that they utilized ATP hydrolysis to transport cargo. In general, all these proteins are not considered "MAPs" because they do not bind directly to tubulin monomers, a defining characteristic of MAPs. MAPs bind directly to microtubules to stabilize or destabilize them and link them to various cellular components including other microtubules.