Table 2. Summary of EC₅₀s from experiments measuring IP₁ accumulation and ERK_1/2 phosphorylation.

Mutants	EC50 (IP1-Elisa)		EC50 (ERK1/2 activity)
	Without L-Phe With L-Phe	With L-Phe	Without L-Phe	With L-Phe
WT	2.9±0.3	2.0±0.1*	3.0±0.1	1.9±0.1*
L173F	1.2±0.1#	1.0±0.1	2.7±0.1#	1.6±0.1*
P221L	1.1±0.1#	0.9±0.1	2.2±0.3#	1.7±0.2
L173P	10.7±1.0#	9.0±0.9	14.9±1.0#	13.5±0.8
P221Q	6.1±0.3#	4.5±0.4*	11.9±0.3#	9.5±0.4*

HEK293 cells were transiently transfected with the WT CaSR or disease-associated CaSR mutants. Cells were then treated with various levels of [Ca²⁺]_o. The EC₅₀s of [Ca²⁺]_o-IP₁ responses and the -[Ca²⁺]_o-ERK_1/2 phosphorylation activity responses were obtained from curve fitting using the Hill equation as mentioned in Method. ^# indicates significance with respect to wild type CaSR, p<0.05 (ANOVA, Dunnett test); ^* indicates significance with respect to the corresponding mutants in the absence of L-Phe, p<0.05 (two-way ANOVA).