As Fra-1 is expressed to high levels in metastatic mammary tumors where uPA (Plau) is also overexpressed and as the Plau gene was demonstrated to be an AP-1 target in other situations, we have addressed here whether Fra-1 could deregulate Plau in such cancers using RNAi-, pharmacological- and locus-wide chromatin immunoprecipitation (ChIP) analyses in a reference metastatic breast cancer cell line. The gene discussed is FOSB; the disease is breast carcinoma.