SPP1 and carcinoma: Previous publications have shown that the degree of immunohistochemical staining of carcinoma cells for the proteins described, OPN (Rudland et al, 2002), S100A4 (Rudland et al, 2000), S100P (Wang et al, 2006), AGR2 (Barraclough et al, 2009) and FANCD2 (Rudland et al, 2010), reflect the level of each particular protein in the specimens.