Pumilio proteins often function in conjunction with other RNA-binding proteins like CPEB, Nanos and deleted in azoospermia-like (DAZL) in the repression of a variety of mRNAs (26,63,64) so it is possible that alterations in the levels or activity of other factors or their interactions with Pumilio are responsible for this differential binding. Here, CPEB1 is linked to Azoospermia.