Figure 1.

Gas1 expression is repressed in Myc-transformed cells. (A) REFs were cotransfected with c-myc and activated H-ras expression plasmids and transformed foci were isolated (9, 10). Randomly selected clones or untransfected REFs were grown to confluence, then cultured in 0.5% fetal calf serum/DMEM for 20 hr. RNA was analyzed by Northern blotting with gas1 and c-myc cDNA probes. A gapdh probe was used to control for RNA loading. (B) Rat-1a cells were stably transfected with expression vectors containing wild-type c-myc (Myc), c-myc deleted of sequences encoding amino acids 132–143 (ΔMB2), or the empty vector; and cell lines were generated. Cells from randomly selected clones were grown to confluence, then cultured in serum-deprived medium as above. RNA was analyzed as in A. (C) Photomicrographs of representative Rat-1a/Myc and Rat-1a/ΔMB2 clones. Magnification, ×320.