A new paper out of Harvard screened embryonic stem cells and found a factor called Lin-28 that inhibits Drosha, which usually cleaves the ends of miRNAs. Lin-28, though, only prevents the processing of miRNAs belonging to the let7 family. The authors suggest that Lin-28 then may prevent miRNA-mediated differentiation in stem cells and some cancers.
Alex Palazzo thinks this is really cool because Lin-28 was one of the factors that helped convert mouse skin cells to pluripotent stem cells. Bayblab's Bayman chimes in, saying, "We already knew that Lin-28 was an RNA-binding protein of developmental significance, so this new finding makes a lot of sense."