To image the localization and dynamics of YAP1 in normal mammary fibroblasts (NF1) and mammary carcinoma-associated fibroblasts (CAF1), we fused EYFP to the N terminus of the protein and generated NF1 and CAF1 stably expressing levels of EYFP-YAP1 similar to the level of the endogenous YAP1 (Figures 1A and S1A), estimated at ∼130,000 EYFP-YAP1 molecules/cell (Figure S1B). The gene discussed is YAP1; the disease is breast carcinoma.