SRP68 and cancer: SRP68/72 heterodimer associates with cell-surface nucleolin in a stable 500-kDa protein complex that includes proteins involved in cancer progression, such as nucleophosmin (NPM1), Wnt-1, the antigen Ku80 and C1q-R, as well as the ribosomal proteins S4 and S6 (Figure 4C) (Krust et al., 2011; Destouches et al., 2012).