The in vivo differentiation proceeds rapidly; for example, cytokine-induced differentiation into melanocytes and cardiomyocytes in vitro requires 6 weeks and 4 weeks, respectively [9, 10], while in vivo, Muse cells express progenitor markers such as NEUROD and achaete-scute homolog 1 (MASH1) within 3 days and maturity markers such as microtubule-associated protein 2 (MAP2) and neuronal nuclei (NEUN) within 7 days after homing into the post-infarct region in a rat stroke model [12]. The gene discussed is ASCL1; the disease is Stroke.