RT-PCR showing the absence of IL11Ra transcript and absence of expression of IL11Ra2 transcript in bone marrow (BM) cells and hematopoietic colonies from cultures stimulated with EPO, SCF, and IL-11. RT-PCR products encoding the deleted exons of IL11Ra locus (A), transcripts from IL11Ra2 locus (B), and HPRT gene (C) were examined by Southern hybridization with radiolabeled internal oligonucleotide probes. Testis that expresses both transcripts is included as a positive control. The product seen in IL11Ra−/− testis (A) is due to the 99% nucleotide identity displayed by transcripts from the two loci in the coding region. Negative (-ve; no cDNA) control is indicated.