Four transcription factors (OCT4, KLF4, SOX2, and c-MYC) reprogram adult cells into stem cells. MicroRNA let-7 is a barrier to reprogramming that inhibits LIN-41, a strong reprogramming factor that is expressed in pluripotent embryonic stem cells. LIN-41 inhibits the transcription factor EGR1, which promotes cell differentiation and is another barrier to reprogramming. (Description from Worringer et al) de9 regulatory pathway PW:0000004 Pathway Ontology 24239284 PubMed The let-7/LIN-41 pathway regulates reprogramming to human induced pluripotent stem cells by controlling expression of prodifferentiation genes. Cell Stem Cell 2014 Worringer KA Rand TA Hayashi Y Sami S Takahashi K Tanabe K Narita M Srivastava D Yamanaka S