Polycystin‑1/PKD1 in Human HUVEC. Polycystin‑1/PKD1 was detected in immersion fixed HUVEC human umbilical vein endothelial cells using Sheep Anti-Human Polycystin‑1/PKD1 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF6270) at 10 µg/mL for 3 hours at room temperature. Cells were stained using the NorthernLights™ 557-conjugated Anti-Sheep IgG Secondary Antibody (red; Catalog # NL010 ) and counterstained with DAPI (blue). Specific staining was localized to cell membranes, cytoplasm and endoplasmic reticula. View our protocol for Fluorescent ICC Staining of Cells on Coverslips .