AG490 (Tyrphostin B42) is an inhibitor of EGFR (IC50: 0.1 μM). It is 135-fold more selective for EGFR than ErbB2, also inhibits JAK2 with no effect to Lyn, Lck, Syk, Btk, and Src.

EGFR:0.1 μM

在体内,AG-490处理可促使小鼠骨髓瘤细胞凋亡,但不影响IL-12诱导的巨噬细胞活化和IFN-γ产量.AG-490（0.5 mg/day）处理裸鼠10天,对JAK2 V617F突变诱导的肿瘤形成及入侵有显著抑制效果.AG-490可大幅降低CD45+和HLA-DR+细胞数,在骨髓中,其可使上述细胞数分别从48% 和46%降低到不可检测水平,这未处理小鼠脾脏中,则从38%和 22% 降低到不可检测水平.

通过诱导程序性细胞死亡,AG-490（5 μM）几乎完全抑制所有ALL 细胞生长,而不影响正常造血功能。AG-490（30 μM）既对Epo诱导的野生型JAK2磷酸化有抑制作用,也对组成型的JAK2 V617F突变型磷酸化有抑制作用。AG-490（50 μM）对表达Bcr-Abl 突变型E255K和T315I的抗Imatinib的BaF3细胞凋亡具有诱导作用。AG-490（60-100 μM）对Stat3sm组成型激活有抑制作用,且抑制自发的（IC50：75 μM）或IL-2诱导的（IC50：20 μM）蕈菌肿瘤细胞生长。AG-490（100 μM）抑制Akt磷酸化和核因子-κB激活,且激活GSK-3β并导致c-Myc降低。AG-490对EGF依赖的HER 14细胞增殖有抑制作用（IC50：3.5 μM）。通过对JAK3和 STAT5a/b活性的抑制,AG-490有效抑制IL-2调节的人T细胞生长（IC50：25 μM）。 尽管AG-490 （5 μM）单独给药不影响FDrv210H细胞增殖,但其可协同增强STI571对p210bcr-abl的抑制从而促进增殖效果。

In vitro kinase autophosphorylation: AG-490 is dissolved in DMSO 10%-Water-ethanol 45%. Crude membrane extracts (0.125 μg/mL) are preactivated with EGF (20 nM) in 50 mM HEPES buffer, pH 7.6, and 125 mM NaCl, for 15 minutes at 4 °C. Autophosphorylation activity of EGFR or ErbB2 kinase is assayed at 4 °C for 30 seconds in V-shaped 96-well plates. Membrane extracts (8 μL) are added to each well containing reaction mixture (12 μL, 50 mM, HEPES, pH 7.4,125 mM NaCl, 12 mM M8Ac2, 2 mM MnCl2, 1 mM NaVO3, 1 μM ATP, and 1 μCi[γ-32P]ATP, final concentrations) and increasing concentrations of AG-490 (4 μL). After termination by addition of hot sample buffer, the samples are run on a 6% SDS-polyacrylamide gel electrophoresis minigel, the gels dried, and autoradiography performed during the linear exposure time period. The receptor bands are scanned densitrometrically, and the results analyzed by the Ez-Fit program. For the analysis of autophosphorylation of JAK2, JAK2 is immunoprecipitated by using anti-JAK2 antibody from lysates of G2 cells pretreated for 16 hours with increasing concentrations of AG-490 (0-50 μM). Immune complexes are then immunoblotted with anti-phosphotyrosine antibody. A dose-dependent inhibition of in vitro kinase activity is demonstrated by assessing JAK2 autophosphorylation.

Cells are exposed to different concentrations of AG-490 for 16 hours. For the determination of cell proliferation, [3H]tymidine (1 μCi) is added 6 hours or more before the cultures are terminated. Cells are then collected and samples counted in a liquid scintillation counter. (Only for Reference)