CACNA1E and colorectal carcinoma: In other words, the fact that βII apparently exists in advanced CRC in non-microtubule form raises the possibility that tubulin does not need to be in a microtubule to promote cancer cell growth and proliferation and that non-microtubule tubulin may constitute a novel and hitherto unexplored target for cancer chemotherapy, and may even have a function in normal cells.