Campbell and Moorehead BMC Cancer 2011, 11:480 http://www.biomedcentral.com/1471-2407/11/480 7-14% and claudin-low tumors have a prognosis similar to luminal B, HER2 enriched and basal-like breast can- cers [47]. Claudin-low subtypes have been reported to most closely resemble mammary epithelial stem cells [47]. Therefore, it is possible that claudin-low tumors present with elevated levels of PDGFRa and PDGFRb, a characteristic that may improve the treatment of this class of tumor. In conclusion, loss of IGF-IR signaling is associated with an increase in PDGFRa and PDGFRb expression. This increase in PDGFRs appears to enhance migration and invasion of mammary tumor cells. This phenom- enon could have important clinical implications in that treatment with anti-IGFIR agents may result in an increase in PDGFR expression and enhanced metastatic capacity of breast cancer cells. Therefore, it may be important to combine anti-IGF-IR strategies with agents inhibiting PDGFR signaling to effectively eradicate tumor cells and to prevent metastasis of any tumor cells that become resistant to the anti-IGFIR therapy. Alter- natively, elevation of PDGFRs may be a characteristic of claudin-low tumors and this feature may be exploited to improve the treatment of this breast cancer subtype. Acknowledgements This work was supported through a grant from the Canadian Breast Cancer Foundation - Ontario Chapter to RM. Authors’ contributions CC participated in design and coordination of the study as well as all of the experiments described in this study and drafting of the manuscript. RM coordinated the study and contributed to drafting of the manuscript. All authors have read and approved the final manuscript. Competing interests The authors declare that they have no competing interests. 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