TEI-9648, an analogue of Vitamin D3 Lactone, acts as a potent and specific antagonist to the vitamin D receptor (VDR). This compound effectively blocks the genomic actions mediated by VDR and the Vitamin D responsive element (VDRE) of 1α,25(OH)2D3. Furthermore, TEI-9648 prevents the differentiation of HL-60 cells induced by 1α,25(OH)2D3, indicating its utility in bone metabolism studies[1][2].

TEI-9648, at concentrations ranging from 10 to 1000 nM, inhibits the alterations in CD11b and CD71 expression that are typically associated with the differentiation of HL-60 cells triggered by 1α,25(OH)2D3. Compared to TEI-9647, TEI-9648 demonstrates a consistently lesser effect in suppressing these alterations. Additionally, TEI-9648 is incapable of inducing differentiation in HL-60 cells, even when applied at a concentration of 1 μM. It does not activate NBT-reducing or α-NB esterase activity on its own. Conversely, it significantly reduces the enhancement of these activities usually caused by 1α,25(OH)2D3 at 0.1 nM in HL-60 cells.