Northern blot analysis of TREM-2 expression after LPS and/or IFNγ treatment. Total RNA was prepared from three mice intracerebrally injected with LPS alone, two mice intracerebrally injected with LPS and IFNγ (L + I), four mice intracerebrally injected with IFNγ alone and three untreated control mice (Con). Total RNA (10 μg) from a single mouse brain was run in each lane. This northern blot was probed with a 32P-labeled TREM-2 cDNA clone (a). To determine the relative abundance of TREM-2 per sample, the same northern blot was re-probed with a RNA loading control, 32P-labeled β-actin cDNA clone (b), and the levels of TREM-2 with respect to those of the loading control were quantified by densitometric analysis (c).