Relative steady-state levels of

c-myb, c-myc, and β-actin transcripts in 32D cells with hematopoietic growth factors or SCFADs. (A) Cells were cultured for 11 days in high IL-3 (25 U/mL, proliferating conditions), low IL-3 (0.5 U/mL, growth-arresting conditions) or no IL-3 (—), death-inducing conditions. SCFADs were tested at 1mM concentrations with 0.5 U/mL IL-3, growth-arresting conditions. Cells were harvested for RNA analysis at days 1 and 11. The first lane of each pair represents RNA from day 1 cultures, the second lane, RNA derived at day 11 (except with arginine butyrate and no IL-3, where RNA was available only at day 1, with no cells surviving to day 11). Total cellular RNA was separated by agarose gel electrophoresis, transferred to nitrocellulose and hybridized with [³²P]-labeled probes specific for c-myc, c-myb, or β-actin, as a control for loading. The autoradiograms are shown here. Experimental conditions: 25U IL-3, cells cultured in 25 U/mL IL-3; —, cultured without any IL-3; in all the other conditions, cells were cultured in 0.5 U/mL IL-3, which is sufficient for survival, but not proliferation. The control was 0.5 U IL-3, with 0.5 U/mL IL-3; B, 0.5 U/mL IL-3 plus 1mM arginine butyrate; G-CSF, 0.5 U/mL IL-3 plus 100 U/mL G-CSF; 1, 0.5 U/mL IL-3 plus 1mM α methyl hydrocinnamic acid; 2, 0.5 U/mL IL-3 plus 1mM 2,2 dimethyl butyric acid; 3, 0.5 U/mL IL-3 plus 1mM 2-2 dimethylmethoxyacetic acid; 4, 0.5 U/mL IL-3 plus 1mM phenoxyacetic acid; 5, 0.5 U/mL IL-3 plus 1mM DL-α-amino-n-butyric acid; EPO, 0.5 U/mL IL-3 plus 3 U/mL erythropoietin. (B) Quantitation of c-myc, c-myb, and β-actin transcript expression levels by densitometric analysis. The treatment conditions identified by number correspond to those described in panel A, and a represents mRNA levels from day 1 cultures; b, day 11 cultures; *, no sample available due to death of the cells by day 11. The data for each transcript are expressed as relative to the levels of that specific transcript found in RNA from day 11 cultures under control conditions (low IL-3, 0.5 U/mL), which were arbitrarily given a value of one. The dashed line in each graph represents the levels of c-myc, c-myb, orβ-actin transcripts in the cells at day 11 under control conditions. The conditions were the same as in part A, and conditions 3-10 had 0.5U/mL IL-3 in addition to 1mM of the SCFA derivatives or cytokines added. 1, 25 U/mL IL-3; 2, no IL-3; 3, arginine butyrate; C, control had 0.5 U/mL IL-3 alone; 4, 100U/mL G-CSF; 5, α methylhydrocinnamic acid; 6, 2,2 dimethylbutyric acid; 7, 2,2 dimethylmethoxyacetic acid; 8, phenoxyacetic acid; 9, α-amino-n-butyric acid; 10, 3U/mL erythropoietin.