RB1 and breast cancer: Thus, Srivastava et al. (2019) identified both race-specific serum biomarkers, such as the tyrosine kinase receptor c-Kit, retinoblastoma proteins (Rb) and vascular endothelial growth factor receptor 2 (VEGFR2), and non-race-specific serum protein biomarkers, such as pyruvate kinase 2 (Pyk2), for racial disparities in BC progression [8].