CACNA1D and bipolar disorder: In addition to these direct effects on LTCC function, specific isoforms of α1 and β LTCC subunit genes can regulate gene expression, with the C-termini of both CaV1.2 and CaV1.3 acting as transcription factors101, 102 and β LTCC subunits also being implicated in transcriptional regulation.103 These details highlight the potential for, but also the difficulties in, refining the molecular targets for a novel generation of brain-selective LTCC antagonists to be developed for use in bipolar disorder and other psychiatric conditions.