passages.id: split_5_test_1351_passage
passages.type: progene_text
passages.text: The effect of IL-6 on the growth of mouse biliary epithelial cells ( BEC ) , in vitro , was tested by comparing BEC obtained IL-6 - deficient mice ( IL-6 ( -/- ) ) to wild - type littermate controls ( IL-6 ( +/+ ) ) , in two different media : simple serum - free media ( S-SFM ) , and complete serum - free media ( C-SFM ) containing forskolin , which stimulates BEC IL-6 production .