Expression data from transfected C2C12 cell lines

Skeletal muscle differentiation is a highly coordinated multistep process in which proliferating mononucleated myoblasts first withdraw from the cell cycle, then differentiate into postmitotic mononucleated myocytes, and subsequently fuse into multinucleated myotubes which finally bundle to form mature muscle fibers. All these processes are controlled by the sequential activation of myogenic regulatory factors, and especially MYOD1 is activated in the early phase to promote the transcription of muscle-specific genes coding for muscle proteins such as alpha-actin, myosin heavy chain and muscle creatine kinase. We used microarrays to detail the global gene expression changes associated with MYOD1 L122R mutation and identified MYOD1 L122R blocked myogenic differentiation and had a MYC-like transcriptional potential. C2C12 mouse myoblast cells were introduced wild type MYOD1, MYOD1 L122R, MYC, and GFP by retroviral infection. For retrovirus production, the pcx4 and pBabe vectors system were used. Retroviruses were obtained by using 293T cells as packaging cells, and were infected into C2C12 cell line and selected with 500 μg/ml Zeocin (Invitrogen, Carlsbad, CA, USA). After selection, RNAs were extracted and processed at MSKCC according to procedures recommended by Affymetrix (Santa Clara, CA, USA).