Ribonuclease protection analysis of RhCE and Rh50 mRNAs. Total reticulocyte RNAs (25 μg) protected fragments of 149 nt and 270 nt from Rh and Rh50, respectively. The ratio between Rh and Rh50 hybridizing signals is equivalent in the Rh-negative control and in DR, whereas it is clearly lower in DAA (see text). The chimeric Rh-Rh50 RNA probe was 568 nt (see the Materials and Methods). A radiolabeledHae III digest of phage øX174 was used as size marker.