Although CD133 is considered a common marker of CSCs in different tumors and its presence has been detected in pituitary tumors (39, 53), it is worth noting that contrasting data have been reported on CD133 expression in TSC spheres derived from pituitary tumors, ranging from positive to negative or low expression (38, 39, 41–43, 54), highlighting the need for the identification of more precise markers for pituitary TSCs. The gene discussed is PROM1; the disease is pituitary tumor.