PGR and adrenal cortex carcinoma: These problems were successively addressed by comparative in vitro assays made on the human H295R adrenocortical carcinoma cell line rich in steroid metabolising enzymes and the metabolically inert K562/R7 cell line, by in vitro measurements of interactions with the human progesterone receptor (PR) and human pregnane X receptor (hPXR) and finally by in vivo assays made on mice xenografted with K562/R7 and NCI-H295R cell lines.