Thirteen is the lucky number for doublecortin.

Doublecortin is a microtubule-associated protein that is essential for normal brain development. A recent report published in Molecular Cell shows that doublecortin associates preferentially with microtubules made of 13 protofilaments, by recognizing a novel site between the protofilaments. These findings explain how doublecortin stabilizes microtubules and provide clues about its function during neuronal migration.