Northern analysis of CIS and A1 mRNA induction in BM-derived macrophages. RNA was isolated from BM-derived macrophages from WT (+/+), HZ (+/−), and null (−/−) mice that had been treated for the indicated time periods with GM-CSF (10 ng/mL), and Northern analysis performed as described in Materials and Methods. The membrane was sequentially probed with CIS, A1, and GAPDH (GAP) probes (A). CIS (B) and A1 (C) mRNA levels normalized to levels of GAPDH (GAP) mRNA were plotted as a function of duration of GM-CSF exposure.