MORF4L1 and Azoospermia: Role for TDP-43 in post-transcriptional gene regulation within the testis is consistent with a similar requirement shown for a number of other RNA-binding proteins, including testis nuclear RNA-binding protein (51), deleted in azoospermia (52), Pumilio RNA-binding protein (53), DEAD-box helicase 5 (54), MRG15 (55), RAN-binding protein 9 (56), and Ptbp1 (57).