RNA was extracted from the tissues of adult mice using Trizol (Invitrogen). A 5 μg of total RNA was electrophoresed in a 1.0% agarose-formaldehyde gel and transferred to a nylon membrane (Zeta-Probe GT, Bio-Rad). The 735-bp cDNA fragment encoding the SAM domain of mr-s was used as a probe for hybridization. Hybridization was performed according to the manufacturer's protocol. Washes with increasing stringency were performed, the last being at 50°C in 0.1× standard saline citrate/0.1% sodium dodecyl sulfate (SDS).