Functions in tethering peripheral heterochromatin to the nuclear lamina during interphase, possibly through the interaction with heterochromatin protein CBX5/HP1 alpha. Might play a role in reattaching heterochromatin to the nuclear lamina at mitotic exit. Promotes myoblast differentiation during skeletal myogenesis, possibly by stimulating transcription factor MyoD activity via binding to CBX5/HP1 alpha. Involved in the positive regulation of the PI3K-Akt-mTOR signaling pathway and in promoting cell proliferation, possibly via binding to GRB2 (By similarity). Interacts (via proline-rich region) with GRB2 (via SH3 domain 2). Interacts (via N-terminus) with CBX5. During interphase, associated with peripheral heterochromatin at the nuclear lamina. Released from the nuclear lamina in mitotic prophase and remains highly dispersed in metaphase. Associates with chromatin at the onset of anaphase and relocalizes to the nuclear lamina in telophase.