A preliminary analysis of the implications of the Zheng et al. data has been submitted as formal paper to a refereed journal by Steele and Lindley.  The Zheng et al.  data strongly imply that the RNA moiety would need to be first A-to-I RNA edited then reverse transcribed and integrated to generate the strong A>>>T strand biased mutation signatures at A:T base pairs observed in all SHM and cancer hypermutation data sets.     Editing (A-to-I) of the DNA moiety at RNA:DNA hybrids in vivo cannot explain the A>>T strand bias because such direct DNA modifications would result in T>>>A strand bias which is not observed in any SHM or cancer data set in vivo.     In this regard Robyn Lindley has also recently discovered that the Ig-SHM-like strand-biased mutations in cancer genome protein-coding genes are also in "codon-context". Lindley has termed this process targeted somatic mutation (TSM) to highlight that somatic mutations are far more targeted than previously thought in somatic tissues associated with disease.   The TSM process implies an "in-frame DNA reader" whereby DNA and RNA deaminases at transcribed regions are guided in their mutagenic action, by the codon reading frame of the DNA.