passages.id: split_8_test_2475_passage
passages.type: progene_text
passages.text: These results suggest that ATF-2 coupled to specific signal transduction cascades plays an important regulatory role in MAG expression at a specific stage of shi / shi oligodendrocyte differentiation , and OPCs grow to become myelin - forming cells with numerous cell processes that wraps around an axon to form a thin myelin sheath .