Fig. 4. Soluble MMP9 enhances tumor growth and angiogenesis. Female BALB/c-SCID mice received subcutaneous injections in both flanks of mock transfected or MMP9-expressing MCF-7 cells. (A) Tumor incidence was calculated as the percentage of palpable tumors per number of injection sites. (B) Tumor size was monitored weekly and tumor growth kinetics over a 14-week period was represented as mean tumor volume±s.e.m. (n=8, in all cases; ^**P<0.05). (C) Tumor vascular profile was evaluated by macroscopic observation (a,d,g,j), Hematoxylin-Eosin staining (b,e,h,k; magnification x400) and blood vessel staining with anti-CD31 antibody (c,f,i,l; magnificatiox200). (D) Blood vessel number was quantified in tumor sections stained with anti-CD31 (^**P<0.05). (E) Vascular perimeter was estimated as the percentage of CD31-stained area per field. The value obtained in sections from mock-transfected tumors was considered as 1 (^**P<0.05).