General 

   20.   Mahmood, et al. Bone Res. 2020. https://www.ncbi.nlm.nih.gov/pubmed/32337090
   21.   de Geus, et al. Biomark Insights. 2017. https://www.ncbi.nlm.nih.gov/pubmed/28690396
   22.   Boonstra, et al. Oral Oncol. 2017. https://www.ncbi.nlm.nih.gov/pubmed/28249642
   23.   Yang, et al. Oncotarget. 2016. https://www.ncbi.nlm.nih.gov/pubmed/27729618
   24.   Boonstra, et al. Oncotarget. 2015. https://www.ncbi.nlm.nih.gov/pubmed/25895028
   25.   Xu, et al. PLoS One. 2014. https://www.ncbi.nlm.nih.gov/pubmed/24465541
   26.   Boonstra, et al. BMC Cancer. 2014. https://www.ncbi.nlm.nih.gov/pubmed/24742002
   27.   Zhang, et al. Mol Cancer Ther. 2013. https://www.ncbi.nlm.nih.gov/pubmed/24061648
   28.   Kenny, et al. Clin Cancer Res. 2011. https://www.ncbi.nlm.nih.gov/pubmed/21149615
   29.   Rabbani, et al. Neoplasia. 2010. https://www.ncbi.nlm.nih.gov/pubmed/20927316
   30.   Van Buren, et al. Cancer. 2009. https://www.ncbi.nlm.nih.gov/pubmed/19484792
   31.   Mazar. Clin Cancer Res. 2008. https://www.ncbi.nlm.nih.gov/pubmed/18794071
   32.   Bauer, et al. Cancer Res. 2005. https://www.ncbi.nlm.nih.gov/pubmed/16140945
   33.   Bauer, et al. Ann Surg. 2005. https://www.ncbi.nlm.nih.gov/pubmed/15849510