Table 3 Key parameters of 5-PL functions fitted by WSSR regression to fold induction/concentration data pairs obtained from various CALUX cell lines incubated with increasing concentrations of 2,3,7,8-TCDD

Number of calibrators

9

8

8

9

9

Number of parameters

5

5

5

5

5

Degrees of freedom (DF)

4

3

3

4

4

WSSR

3.9258

1.4241

0.2661

0.5751

3.8570

Chi-square-to-DF ratio, χ²/DF

0.9814

0.4747

0.0887

0.1438

0.9642

Maximum fold induction

136

20.6

8.75

10.5

31.2

SE of max. fold induction

3.26

1.14

0.29

0.40

0.63

EC70

22.3

19.8

14.0

9.21

50.5

pmol/L

EC50

11.4

5.52

7.89

5.28

23.5

pmol/L

Inflection point (c)

7.22

3.67

12.0

4.63

15.0

pmol/L

SE of c

0.74

2.49

1.60

1.20

3.57

pmol/L

Slope (b)

1.17

0.90

1.70

1.48

1.03

SE of b

0.08

0.17

0.28

0.22

0.09

Asymmetry factor (e)

1.51

1.81

0.63

1.15

1.42

SE of e

0.15

0.96

0.14

0.32

0.26

Fold induction at 1.0 pmol/L

4.47

2.44

1.53

1.62

1.56

Fold induction at 0.3 pmol/L

1.46

1.33

1.16

1.10

1.12

Background contribution 50%^a

0.46

0.74

1.78

1.37

1.60

pmol/L

Minimum fold induction

1.00

1.00

1.00

1.00

1.00