Indirubin, the core chemical structure of meisoindigo, did not inhibit leukocyte chemotactic migration, and meisoindigo does not regulate pAKT/AKT or pERK/ERK level. (a) Chemical structure of indirubin (I) and meisoindigo (M). Meisoindigo is a synthetic derivative of indirubin with a methyl substitution at N element. (b,c) Tg:zlyz-EGFP embryos (3dpf) with tail transection were treated with vehicle (n = 15), indirubin (I, 100 μM, n = 14) or meisoindigo (M, 100 μM, n = 11), respectively. Leukocytes that migrated to the highly inflamed regions [white boxes in (b)] at 6 hptt were quantitatively analyzed (c). The p values were annotated as obtained from a two-tailed t test. (d) Westernblot analysis showing the effect of meisoindigo on the selected signaling pathway components. 20 zebrafish embryos (3dpf, n = 20) with tail transection were treated with vehicle, meisoindigo or indirubin at the indicated concentration from 0 hppt to 6 hptt, respectively. Then, the lysate of whole zebrafish embryos was subjected to westernblot analysis for detecting pAKT/AKT or pERK/ERK level.