SPP1 and autoimmune disease: Moreover, OPN has been implicated in the development of a number of pathological conditions, such as cancer (Afify et al. 2009; Ramaiah and Rittling 2008), autoimmune disorders, infections (Glas et al. 2011; Mishima et al. 2007), asthma (Cantor 1995; Carecchio and Comi 2011; Frenzel and Weiss 2011; Harris and Sadiq 2009; Konno et al. 2011; Murugaiyan et al. 2008; Zandman-Goddard and; Shoenfeld 2003), cardiovascular diseases (Singh et al. 2007), as well as kidney and liver diseases (Cao et al. 2012; Ramaiah and Rittling 2008).