It was reported that Cdc25A is suppressed by miR-21 in colon cancer cells29 and that FoxO3a induces apoptosis of lung cancer cells by negatively regulating miR-21 in response to doxorubicin.28 We found that a miR-21 mimic is sufficient to block Cdc25A mRNA and protein induction by Aβ and that miR-21 is downregulated in Aβ-treated neurons by a mechanism requiring FoxO transcription factors. The gene discussed is CDC25A; the disease is lung cancer.