PB Inc⁻CD34⁺ cells that express SDF-1 are in cycle.

Freshly isolated PB CD34⁺ cells were purified immediately after density gradient separation (Inc⁻). Cell cycle status of SDF-1–expressing cells was determined by using a dual staining for Ki67 expression and SDF-1 intracellular expression as indicated in “Materials and methods.” (A) The Ki67 expression allowed discrimination of G₀ (Ki67⁻) from G₁+S+G₂/M (Ki67⁺) cells. Arbitrary quadrants were drawn on the basis of isotype-matched negative control. (B) The logarithm fluorescence of intracellular SDF-1 is expressed in channel numbers. Histograms show results from staining with SDF-1 mAb (solid histogram) and results from staining with irrelevant isotype-matched control antibody (open histogram). The histograms shown are for one experiment representative of the 3 performed.