Differential gene expression in FDCP1 cells after IL-3 withdrawal. (a) Comparative Atlas array hybridization with cDNA probes derived from FDCP1 cells after 0 h (left) and 2 h (right) of IL-3 deprivation. Filters were scanned with a PhosphoImager (Molecular Dynamics) and analyzed with the AtlasImage 1.5 software. (b) Relative changes in gene expression on a log scale. 1, no regulation; > 1, upregulation; < 1, downregulation. Note that the apparent downregulation of Bcl-2 could not be confirmed on northern blots. Induction of c-kit and Chop10 (asterisked) was observed only on arrays hybridized to cDNA recovered from cells after 8 h of factor deprivation. (c) Northern blot analysis of transcripts identified as differentially expressed by the AtlasImage 1.5 software. Poly(A)+ RNA (2.5 μg) prepared after 0, 2, 4, 6 and 8 h of IL-3 deprivation was fractionated on formaldehyde gels, blotted onto nylon filters and hybridized with 32P-labeled gene-specific probes.