passages.id: split_4_validation_1247_passage
passages.type: progene_text
passages.text: By using a combination of solid phase protein kinase assays , transient transfections in cells , and analysis of endogenous proteins in stably transfected Madin-Darby canine kidney cells , we found that MRK-beta preferentially activates ERK6 / p38gamma via MKK3 / MKK6 and JNK through MKK4 / MKK7 .