Table 2. Output of Linear Regression between RGA Protein Concentration and EXPA3 Promoter Activity and Cell Volume across Different Cell Types of the Expanding Arabidopsis Root.

	Coefficient		se		t-Value		P Value
Cell Type	RGA and Cell Vol.	EXPA3 and Cell Vol.	RGA and Cell Vol.	EXPA3 and Cell Vol.	RGA and Cell Vol.	EXPA3 and Cell Vol.	RGA and Cell Vol.	EXPA3 and Cell Vol.
Epidermis	−0.00575	0.10873	0.023	0.013	−0.242	8.482	0.809	3.71·10−16
Cortex	0.00512	0.07099	0.012	0.012	0.426	5.714	0.671	4.88·10−8
Endodermis	0.00487	0.14115	0.018	0.0164	0.278	8.614	0.781	2.77·10−15

Roots were imaged and both cell geometric data and quantitative protein concentration used to fit linear models to explain these quantitative relationships. A P value < 0.05 indicates a significant relationship.