Role of SDF-1α in the proliferation of BCCs from cocultures. (A) Cocultures were performed with SDF-1 knockdown T47D, DU4475, and ZR-75-30. Control cocultures were untransfected or transfected with vector alone (pPMSKH1). When the untransfected cells achieved 80% confluence, 5 ng/mL SDF-1α was added to each culture. After 48 hours, confluence was achieved and, at that time, the nonadherent cells were discarded and the BCC subset was selected from the adherent population and then counted. The results are presented as the mean cell counts ± SD, n = 8. *P < .05 versus cultures with untransfected BCCs or cultures with untransfected cells and exogenous SDF-1α. **P > .5 versus untransfected BCCs. ***P < .05 versus untransfected/media alone. (B) The experiments described in panel A were repeated with the following modifications: 24 hours after the addition of SDF-1α,1 μCi/mL TdR was added and, after an additional 24 hours, the BCCs from both the adherent and nonadherent population were analyzed for TdR incorporation. The total disintegrations per minute (dpm) for untreated, SDF-1α–treated, and SDF-1 knockdown cells are presented as the mean ± SD, n = 5. (C) Representative cultures with T47D alone are shown for untransfected cells (i) and similar cells knockdown for SDF-1 (ii); panels iii-iv show the same clusters of cells at a higher magnification. At 80% confluence, cocultures, BCCs were selected and then counted. The results are presented as the mean ± SD of total cell counts. Images were visualized using a Nikon Eclipse TE 300 microscope (Nikon, Tokyo, Japan) equipped with a 10×/0.45 numerical aperture (NA; i-ii) or a 40×/0.8 NA (iii-iv) objective. Images were acquired using an RE Color 2.2.1 camera and SPOT for Windows version 3.5.9 (Diagnostic Instruments, Sterling Heights, MI), and were processed using Adobe Creative Site 2 Premium (Adobe Systems, San Jose, CA).