IGF1 and cancer: However, much less is known about the expression profile of the IGF-I splice variants and the potentially distinct biological roles of the IGF-I isoforms in the pathophysiology of various types of cancer (Siegfried et al., 1992; Kuo and Chen, 2002; Armakolas et al., 2010; Koczorowska et al., 2011; Philippou et al., 2011; Kasprzak et al., 2012).