This exciting paper addresses a mystery in tumor virology as to how, Bovine Leukemia Virus (BLV), a retrovirus that is frequently recovered in B cell lymphomas, contributes to oncogenesis. microRNAs have rapidly become significant players in cell cycle regulation/tumorigenesis and are also expressed by viruses. Although most viral derived microRNAs are found in DNA viruses, this paper bioinformatically discovered and subsequently verified the expression of many in BLV. Interestingly, they found that one of these microRNAs, BLV-miR-B4, displayed significant homology to a host microRNA miR-29a. What makes this so significant is miR-29a has been shown previously that when overexpressed, cells display hyperproliferative phenotypes. Finally and most importantly, this group showed that host tumor suppressing genes HBP1 and PXDN are both targeted by miR-29a and the BLV-miR29 analog. Thus, BLV-miR-B4 may be a functional analog of miR-29a and by targeting tumor suppressing mRNAs and possibly preventing their translation, could drive B cell lymphoma oncogenesis.