STAT3 and acute promyelocytic leukemia: Also, As2O3 inhibits protein tyrosine kinase, thereby indirectly decreasing activation of STAT proteins [42].Therefore, downregulation of STAT3 has been considered one of the mechanisms of action of As2O3 in acute promyelocytic leukemia(APL).We found STAT3 activated in AFPGC cells, and As2O3 could downregulate STAT3 mRNA expression and STAT3 and pSTAT3 protein expression.