CXCL12 and synovial sarcoma: Purified SS cells from 5 patients (Table S2), cultured at high density in complete medium with or without SDF-1 or CCL21, demonstrated that both chemokines significantly enhanced proliferation, although to lesser extent than T-cell growth factors like IL2/IL7; we assessed that rapamycin inhibited this chemokine-induced effect (upper panel, Fig. 3c).