Identification of 1,25(OH)₂D₃ -modulated genes transcription by DD-RT-PCR. DD-RT-PCR was performed on total RNA from unstimulated (lane C) and 1,25-(OH)₂D₃ –stimulated neonatal monocytes (lane D) as described in the Materials and Methods using primers T₁₁CA and Ltk₃ . Arrows indicate interesting labeled DNA products. Amplified double-stranded DNA corresponding to the amplification of 15-PGDH is noted as “b.” Total RNA samples pretreated by RNase A were used in the same experimental conditions to confirm the absence of genomic DNA contamination (lanes A, untreated cells; lane B, 1,25-(OH)₂D₃ –treated cells).