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Figure 3. Proposed mechanism for the up-regulation of GlcAT-I expression by elevation of intracellular calcium and consequences on GAG chain synthesis. The rise in intracellular calcium leads to the activation of MEK/ERK pathway, which in turn stimulates GlcAT-I gene transcription by promoting the binding of Sp1 factor to the promoter. Up-regulation of GlcAT-I expression may represent a possible mechanism leading to the stimulation of GAG synthesis by calcium-dependent pathway.
