“…The expression of the homeobox gene HB9, a terminal MN transcription factor in the developing spinal cord, was highest at the first time-point measured, day 8, and decreased from then onward (Figure 6I). HB9 expression declines during development (Heindorf et al, 2019;Arber et al, 1999) and longitudinal gene expression studies revealed that it begins to appear 3-5 days after addition of patterning molecules in mouse EB-based ESC-derived MN differentiation protocols (Wichterle et al, 2002;Soundararajan et al, 2006;Amoroso et al, 2013) and 7-14 days in human EB-based iPSC-derived protocols (Amoroso et al, 2013). Our HB9 expression results indicate that in our SCO protocol the specification of MN identity occurred at an early stage.…”