Treatment

Experiment

Experiment 15


1

2

3

4

5

AVG of [[1]] [[2]] (±SD)


DMSO

1.06

0.91

0.96
  
ut

1.00

1.00

1.00

1.00

1.00

2 h

TQ

0.90

0.87

0.66

0.47
 
PI3Kinh.

0.69

0.84

0.86

0.57

[1] TQ + PI3Kinh.

0.61

0.47

0.46

0.41
 
[2] Multiplication of TQxPI3KInh.

0.61

0.73

0.56

0.27
 
Difference[1] [2] at 2 h

−0.01

−0.26

−0.10

0.15
 
−0.06 (±0.17)*

4 h

TQ

0.93

1.07

0.76
 
0.92
 
PI3K inh.

0.67

1.04

0.64

0.69

[1] TQ + PI3K inh.

0.59

0.53

0.47

0.62

[2] Multiplication of TQxPI3KInh.

0.62

1.11

0.49

0.63

Difference[1] [2] at 4 h

−0.03

−0.59

−0.02
 
−0.01

−0.16 (±0.28)**

 RKO cells were treated with TQ, PI3K inhibitor or with a combination of both substances for 2 h or 4 h to test for syngergistic or additive effects on the dephosphorylation of GSK3β. 5 different Western blots were performed and the relative ratios of pGSK3β and total GSK3β protein levels were calculated using the program Image J. Mathematically, when effects are measured as proportions, the additive effect of two substances is the multiplication of the two values resulting from the single treatments. The mathematical product of both treatments is only minimally deviating from the actual values for the double treatment resulting from the Western blots. The nullhypothesis of no mean difference cannot be rejected at either time point (Ttest, pvalue *0.56 (2 h) and **0.34 (4 h)). While this result is in itself no proof of additivity, a closer inspection of the calculated differences shows that the assumption of additivity is indeed reasonable: In experiments 1, 3 and 5 the differences are very close to zero. Experiments 2 and 5 show stronger deviations, however in opposite directions and the resulting mean differences are close to zero for both time points.