Figure 4.

SCS-873 inhibits the in vitro proliferation of cells expressing integrins α_vβ_{3 and} α_vβ₅. Shown are proliferation assays based on [³H]thymidine incorporation during DNA synthesis. (A) SCS-873 inhibits the in vitro proliferation of human KS cell line SLK with an IC₅₀ of ≈1 μM. Note that the inhibitory activity of SCS-873 is neither diminished nor enhanced by mAb 38C2. (B) SCS-873 inhibits the in vitro proliferation of mouse endothelial cell lines SVEC, MAEC, and MS1 with an IC₅₀ in the range of 1–10 μM. By contrast, the in vitro proliferation of human colon cancer cell line SW1222, which expresses neither integrin α_vβ₃ nor α_vβ₅, is not inhibited by SCS-873.