Analysis of DS–IL-6r in MMPC by RT-PCR, sequencing, and qRT-PCR. (A) RT-PCR fragments of the consensus IL-6r (398 bp) and DS–IL-6r (304 bp) in MMPCs from 5 untreated patients. Lane 1, 100-bp DNA ladder (Invitrogen); lane 2, rs2228145 homozygous A patient; lane 3, rs2228145 homozygous C patient; lane 4, rs2228145 heterozygous patient; lane 5, rs2228145 homozygous C patient; and lane 6, rs2228145 homozygous C patient. (B) Alignment of partial sequences from RT-PCR fragments of the DS–IL-6r and the consensus IL-6r transcripts. The deleted 94-bp region can be seen in the alignment. Underlined sequences represent primer targets, and boxed sequences represent reporter target for qRT-PCR of DS–IL-6r. (C) qRT-PCR of DS–IL-6r expression in 106 baseline MM PCs. The rs2228145 allele C and chromosome 1q21 amplification are associated with higher DS–IL-6r expression levels.