Table 1.

gdt1⁻ cells do not influence discoidin expression in gdt1⁺ cells

DAG cells (%)	L8 cells (%)	β-Gal activity (%)
100	0	100
90	10	87
60	40	48
30	70	32
10	90	9
0	100	3

L8 cells and DAG cells (which express β-galactosidase (β-Gal) under the control of the discoidin Iγ promoter) were mixed at the indicated ratios and grown in KA suspension to a density of 1 × 10⁶. Cells were harvested, and β-galactosidase activity was determined by 2-nitrophenyl-β-d-galactopyranoside assay. β-Galactosidase activity is given as the percentage of activity found in 100% DAG cells. The values correspond approximately to the amount of DAG cells in the mixture, indicating that gdt1⁻ cells do not secrete a factor that can enhance discoidin transcription in the tester strain.