Luciferase reporter assays performed in C-28/I2 cells were cotransfected with a pGL2B(−577/+3428)COL2A1 reporter construct (pGL2B-4.0-Luc) together with (A) expression vectors encoding sub-optimal concentrations of L-Sox5, Sox6, or Sox9, alone or in combination, or (B) expression vectors encoding Sox9 and Sox6, alone or in combination with expression vectors encoding ELF3. *indicates p<0.001 vs. Sox5, Sox6, Sox9 and Sox5,6; #indicates p<0.05 vs. Sox5,9; ***indicates p<0.001.