Identification of mRNA in BMSC by ISH using digoxigenin-labeled probe. BMSC were cultured in the absence (A) or in the presence (B, C, D) of PAF for 20 hours and hybridized with PRL cDNA probe (A, B, and C) or with poly dT probe (D). The specificity of the reaction was assessed by pretreating PAF-stimulated cells with RNAse before hybridization (C). These findings were confirmed in other two experiments.