Northern blot analysis of FLVCR, RDR, and GALVR mRNA levels in RNA from HeLa, K562, and human bone marrow (HuBM) cells. Total RNA extracted from the indicated cells was separated on agarose gels and transferred to a nylon filter. The filter was sequentially probed with a DNA fragment containing FLVCR and GALVR sequences (A), a DNA fragment containing RDR and GALVR sequences (B), and a DNA fragment containing actin sequences (C). The approximate sizes of the mRNAs are indicated at the right. Blots in panels A and B were exposed for approximately 48 hours; panel C, approximately 10 hours.