I have been trying a variation of iCLIP, the irCLIP protocol by Zarnegar et al., and came across your google document with questions and answers. First of all, it is very useful, thank you very much. Secondly, I have tried the protocol with one of the hnRNP proteins and after the library preparation (which I think follows Flynn et al., Fast-iCLIP), I see a strong peak at 148 bp and a fainter smear ranging from ~120-200 bp. The empty PCR products are reported to be 137 bp. I was wondering if this pattern is normal to be seen by bioanalyzer and if not, have you ever experienced a discreet stronger band in your iCLIP final libraries.