FOCAL POINT (Left to right) Masaki Inagaki, Akihito Inoko, Makoto Matsuyama, and colleagues (not pictured) reveal how proliferating cells suppress the formation of primary cilia. The centriolar protein trichoplein inhibits cilia assembly by activating the Aurora A kinase. When cells exit the cell cycle, however, trichoplein is lost from the centriole that becomes the ciliary basal body, allowing ciliogenesis to proceed in quiescent cells. Unlike control cells (second from right), proliferating RPE1 cells lacking trichoplein (far right) aberrantly assemble primary cilia (stained for acetylated tubulin, green). This results in cell cycle arrest, suggesting that the vertebrate cell cycle can be regulated by cilia assembly and resorption.

PHOTOS COURTESY OF THE AUTHORS