Neuronal differentiation of miR-124a-1/2/3 TKO ES cells.A, Northern blot analysis of miR-124a in the control and miR-124a-1/2/3 TKO cells. B, scheme of neuronal differentiation induction from mouse ES cells. C, Northern blot analysis of miR-124a in the control cells at the indicated time points. D, phase-contrast view of the control and miR-124a-1/2/3 TKO cells at the indicated time points. E, immunostaining of the control and miR-124a-1/2/3 TKO cells at N2/B27 day 1 using an anti-Tuj1 antibody (a marker for neurons). ES, embryonic stem; GSKi, GSK3 inhibitor; MEKi, MEK inhibitor; miR-124a, MicroRNA-124a; TKO, triple knockout.