Fig 1. Comparative effects of 25(OH)D₂, 25(OH)D₃, 1,25(OH)₂D₂ and 1,25(OH)₂D₃ on cell numbers.

Human BMSCs (panels A&B) and 2T3 cells (panels C&D) received separate treatments over 24 h with either 50–1000 nM 25(OH)D₂/D₃ or 0.05–1 nM 1,25(OH)₂D₂/D₃. Cell numbers were measured by MTS. Mean ± SEM percentage values from triplicate experiments have been presented as fluorescence units (RFU) from treated cells relative to untreated control (vehicle). # P<0.05, ## P<0.01, ### P<0.001 for comparisons between the treatments and the control; * P<0.01 for comparisons between the D₂ and D₃ metabolites.