Calbindin-D 28k has been reported to be a facilitator of calcium diffusion and to protect against apoptotic cell death. Most recently, we found that the presence of calbindin-D 28k results in reduced calcium influx through voltage-dependent L-type Ca 2+ channels and enhanced sensitivity of the channels to calcium dependent inactivation. Co-immunoprecipitation and GST pull down assays indicate that calbindin-D 28k interacts with the C-terminus of the L-type calcium channel alpha 1c subunit (Ca v 1.2). This is the first report of the binding of calbindin to a calcium channel and provides new insight concerning mechanisms by which calbindin acts to modulate intracellular calcium. Besides calbindin, another major target of 1,25(OH) 2 D 3 is 24(OH)ase, which is involved in the catabolism of 1,25(OH) 2 D 3 . We reported that C/EBPβ is a major transcriptional activator of 24(OH)ase that cooperates with CBP/p300 in regulating VDR mediated 24(OH)ase transcription. Recently, we found, in addition to p160 coactivators, that SWI/SNF complexes (that facilitate transcription by remodeling chromatin using the energy of ATP hydrolysis) are also involved in VDR mediated 24(OH)ase transcription and functionally cooperate with C/EBPβ in regulating 24(OH)ase. These findings define novel mechanisms that may be of fundamental importance in understanding how 1,25(OH) 2 D 3 mediates its multiple biological effects.