Proposed explanation for previously identified insertional RNA editing sites in human. Based on our indel analysis of false positives and EST data in, we hypothesize that the two “insertional RNA editing sites” may be signatures of novel splice junctions. For h1.0, the base "G" in the EST sequence is a mismatch compared to the genomic base "C" which is present in all EST sequences which have 4 bp upstream of the "editing site". For HMGN1, the only one EST sequence which supports "editing" also displays a mismatch ("G" in the genome and "C" in the EST sequence) upstream of the "editing site". The "AG" marker in the red box in the H1.0 and HMGN1 sequence may serve as an unknown 3' splice site.