SPP1 and breast carcinoma: The DNP hapten was hybridized to a VEGF or OPN aptamer via complementary sequences as described in ref.24 To determine whether tumor growth can be inhibited in DNP-immune mice treated with VEGF–DNP or OPN–DNP conjugates, Balb/c mice immunized with DNP-KLH or with KLH were implanted subcutaneously with 4T1 breast carcinoma tumor cells and 7–8 days later when tumors became palpable mice were treated with VEGF–DNP or OPN–DNP conjugates.