passages.id: split_5_test_1593_passage
passages.type: progene_text
passages.text: In the presence of stimulatory concentrations of GLP-1 ( 0.1 -- 100 nM ) on rINS1 activity , inhibition of p38 mitogen - activated protein kinase ( p38 MAPK ) using SB 203580 resulted in a marked increase in promoter activity ( maximum 3 - fold ) over GLP - 1 alone , as determined by rINS1 promoter - luciferase reporter gene expression .