GSK3B and pheochromocytoma: In glioma cells (H4) and phaeochromocytoma-differentiated neurons (PC12), GSK3β inhibition using lithium chloride (LiCl) causes an increase in expression of PGC-1α1 and PGC-1α4 isoforms14, but neither cell type expresses the B1E2 isoform which is the dominant form of PGC-1α in primary cortical neurons.