Playing Ping Pong with Pins: Cortical and Microtubule-Induced Polarity

Cortical cell polarity controls mitotic spindle orientation in many cell types. In this issue of Cell, Siegrist and Doe (2005) turn this around and show that the transfer of polarity information between the cortex and the spindle is not just one way. In Drosophila neuroblasts, the spindle also has polarizing activity on the cortex