TRANCE down-regulates the expression of Id genes during osteoclastogenesis. RAW264.7 cells (A) and BMMs (B) were cultured for the indicated time in the presence of TRANCE (A) and M-CSF, and TRANCE (B), respectively. Total RNA was collected from each time point and analyzed by Northern blot using probes for Id1, Id2, Id3, and TRAP. The relative amounts of Ids were shown under the figures (B). Arrows indicate ribosomal RNA; arrowheads, the bands representing Id1, Id2, or Id3.