Reverse transcription

In this podcast, you mentioned a couple of times a connection between retroviruses and cancers. Are some/many/all cancers caused by viruses?

In all figures that show the RNA genome of retroviruses, the two RNAs are shown in such a way that suggests that there is homology between the two strands - downstream from the pbs and between the pol and env genes. However, since the two RNAs are shown in the same 5' to 3' orientation, it is impossible for the two RNAs to hybridize, since that orientation is parallel, not antiparallel. Is this just a case of an artful presentation being copied over and over again without artists thinking about biological reality?

There is base-pairing between the two retroviral RNAs at many points,
but clearly the complementarity is not co-linear. It's not impossible
for the two RNAs to hybridize in the 5'-3' orientation as shown. For
example, bases 12-18 might hybridize with bases 24-30.

Right. Those figures of retroviral RNA have bugged me for years, since they imply something that's not possible.