SOX2 and colorectal carcinoma: Moreover, to test if Sox2 is expressed in the progenitors of CRC, we turned on EYFP in Sox2-expressing cells of the early telencephalon before CRC differentiation started, at E9.5 (via a Sox2-CreERT2 transgene and a lox-stop-lox reporter of Cre activity, electronic supplementary material, figure S1), and found that these cells differentiated into Reelin-expressing CRC in the hippocampal fissure and the cortex (electronic supplementary material, figure S1).