tokens: Expression of constitutively active MEK1 , the kinase that activates ERKs , or overexpression of ERK2 , but not JNK1 , inhibited Stat3 activation .
folded_tokens: expression of constitutively active mek1 , the kinase that activate erk , or overexpression of erk2 , but not jnk1 , inhibit stat3 activation .