PDGFRA and renal cell carcinoma: Interestingly, platelet-derived growth factor signaling enriched in stromal cells has previously been shown to mediate brain metastasis in breast cancer [37] and multiple tyrosine kinase inhibitors such as sorafenib and sunitinib inhibiting PDGFRβ and PDGFRα are available and FDA-approved for advanced renal cell carcinoma [38].