Immunoblots revealed increased levels of phospho-Cdc2 (Tyr-15) in ALL cells treated with SF, suggesting that SF inhibits the Cdc2/Cyclin B1 complex by increasing phosphorylation of Cdc2 (inactive) despite elevated levels of Cyclin B1 (Fig. 4A). Here, CCNB1 is linked to acute lymphoblastic leukemia.