SOX2 and brain neoplasm: Nonetheless, a few notable examples include the melatonin-induced regulation of Elk-1, a member of the ternary complex factors (TCFs) within the ETS (E26 transformation-specific) domain superfamily, a transcription factor implicated in neurodegeneration, neuroprotection, and brain tumor proliferation, which regulates Sox2, Oct4, and Nanog [49], and melatonin has been shown to substantially activate Elk-1 [50].