Predominant expression of zeta and epsilon globin genes in human leukemia K-562(S6) variant cell line

In the human leukemia K-562(S6) cell line (a) the accumulation of alpha-globin chains is low or absent, (b) zeta-globin gene expression is correlated with expression of epsilon-chains and (c) the genes responsible for the terminal cell division are not operated within 8-12 cell cycles, while K-562(S6) cells are fully induced to erythroid differentiation.