Enzymatically active VAP-1 dimers are synthesized already at week 11 of human gestation. (A) Tissue lysates were prepared from the indicated fetal and adult tissues, and analyzed by immunoblotting with anti-VAP-1 mAbs. In addition, the samples from a 40-week liver were precleared with anti-VAP-1 (VAP-1 depl)- or control mAb (contr depl)-armed beads, as indicated. The molecular-weight markers are indicated on the left. (B) Tissue lysates were prepared from the indicated tissues. The specific enzymatic SSAO activity was measured using the fluorometric assay, and is expressed as picomols of H₂O₂ produced per 1 μg protein in 1 hour. The results from a representative assay, out of 2 with similar results, are shown.