Table 3. Output of the Linear Regression between RGA Protein Abundance and EXPA3 Promoter Activity across Different Cell Types of the Arabidopsis Root.

Cell Type	R2	P Value
Epidermis	0.512	0.014
Cortex	0.114	0.457
Endodermis	0.381	0.044

R² indicates the fraction of the variation in EXPA3 promoter activity accounted for by RGA. A P value < 0.05 represents a significant relationship.