Due to limitations in cell number and case-to-case variations of CD34+-derived erythroid cells, which were likely the influence of maternal and neonatal factors, e.g., maternal age, gestational age, birth order, birth weight, infant sex, and length of umbilical cord [32, 33], human-derived erythroblastic leukemia K562 cells were used to further investigate the regulatory mechanisms behind terminal erythroid differentiation, which theoretically starts from proerythroblasts that proliferate and differentiate to generate reticulocytes [22]. Here, CD34 is linked to acute erythroid leukemia.