RPS6 and acute lymphoblastic leukemia: The effect of CIGB-300 on the phosphorylation of two CK2 direct substrates involved in T-ALL biology (PTEN and Akt), as well as downstream signaling players forkhead box O1/3 (FoxO1/3), cyclin-dependent kinase inhibitor 1B (CDKN1B/p27kip1) and ribosomal protein S6 (S6), was evaluated in HPB-ALL cells.