Skip to main content
. 2001 Nov 20;98(24):13613–13618. doi: 10.1073/pnas.231499098

Figure 4.

Figure 4

JSP-1 activated JNK through activation of MKK4. (A) Flag-tagged MKK4 was coexpressed with a control vector (lane 1), plasmid encoding wild-type JSP-1 (lane 2), or the inactive C→S mutant form of JSP-1 (lane 3). In addition, cells expressing Flag-tagged MKK4 were stimulated with 500 mM sorbitol (lane 4). Cell lysate was resolved by SDS/PAGE, and the MKK4 activity was measured by immunoblotting with antiphospho-SEK antibody (Upper). The amount of MKK4 in each lane was determined by immunoblotting with anti-Flag antibody (Lower). (B) Myc-tagged Jnk was coexpressed with control vector (lane 1) or hemagglutinin-tagged wild-type JSP-1 in the absence (lane 2) or presence of the inactive K→R mutant form of MKK4 (lane 3). Jnk activity was determined by immune-complex kinase assay (Top). The amount of Jnk in each reaction was determined by immunoblotting with the anti-Myc antibody 9E10 (Middle), and the expression of JSP-1 was determined by immunoblotting with the 12CA5 antibody (Bottom).