FOXO1 and cancer: When cells were treated with MK-801, primers flanking a FOXO consensus binding site specifically amplified DNA sequences immunoprecipitated by anti-phospho-FOXO antibody, indicating that FOXO1 is able to bind the TXNIP promoter in vivo, which supports the result of the increase of luciferase activity in Figure 4B. Next, we examined the effects of TXNIP on MK-801-induced cancer cell growth inhibition.