STAT3 and erythroleukemia: Analysis of cell lysates from TPO-responsive human erythroleukemia HEL cells39 stimulated with rhTPO or TMP-PA8-containing supernatants by phosphokinase array revealed that phosphorylation of signal transducer and activator of transcription (STAT)3, STAT5, Erk1/2, and adenosine 3′,5′-cyclic monophosphate (cAMP)-responsive element-binding protein (CREB) is enhanced in rhTPO- and TMP-PA8-stimulated HEL cells compared with unstimulated cells (Supplementary Figs. 17a, b).