Expression of mRNA encoding tumor necrosis factor receptor superfamily, member 11a (TNFRSF11A , wild type receptor activator of NF-kB , wt RANK), TNFRSF11A_Δ9 (RANK-a), TNFRSF11A_Δ8,9 (RANK-b) and TNFRSF11A_Δ7,8,9 (RANK-c) in breast cancer cell lines and breast cancer samples. A. Agarose gel electrophoresis (2%) of PCR products using primers P1 and P2 depicting TNFRSF11A and the identified alternative splice variants in MDA-MB-231, SKBR3, MCF7, MDA-MB-468, T47D and MCF10A breast cancer cell lines. vTNFRSF11A_exon9a was observed only in SKBR3 and after cloning and sequencing was identified as a TNFRSF11A variant encompassing exons 6, 7, 8, 9a and 10. Splice variant TNFRSF11A_Δ7,8,9 is in bold. B. TNFRSF11A_Δ7,8,9 (RANK-c) relative mRNA expression levels in a panel of breast cancer cell lines and the non-tumorigenic epithelial cell line MCF10A; values obtained for MCF10A were set to 100. C. Relative mRNA expression levels of variant TNFRSF11A_Δ7,8,9 (RANK-c) in a panel of formaldehyde-fixed paraffin embedded (FFPE) invasive ductal breast carcinoma samples analyzed against tumor histological grade and proliferation index Ki-67, respectively. D. Relative mRNA expression levels of TNFRSF11A (wt RANK) in the same panel of invasive ductal breast carcinoma samples plotted against tumor histological grade.