(Top) Naïve C3H/HeN mice were injected intraperitoneally with PC61 mAb or Y13 control mAb, respectively. Mice were sacrificed at the indicated time points and splenocytes were analyzed by FACS after staining with anti-CD4, anti-CD25, and anti-FoxP3. The percentage of triple-positive cells is presented. (Bottom) Lung metastases were established in C57BL/6 mice via tail vein injection of D5lacZ cells. 2 days later, animals received intraperitoneal injections of PC61 or Y13 mAbs. Mice were sacrificed at the indicated time points, splenocytes were analyzed by FACS as described above and the percentage of triple-positive cells was determined.