Correction to: Cell Research https://doi.org/10.1038/cr.2013.37, published online 12 March 2013.

It has been brought to our attention that our paper1 published in Cell Research in 2013 contains duplicated panels in Fig. 3A (H-X1_30-51 and mmu-let-7d). By examining the lab records, we found that the gel image of H-X1_30-51 appeared to be used as a place holder for mmu-let-7d (the loading control) when the original figure was first assembled. Unfortunately, it was never replaced by the real mmu-let-7d gel image. We repeated the PCR assays and added the mmu-let-7d gel image to the corrected Fig. 3A. This correction does not affect the major findings and conclusions of this work. We apologize for this oversight.