NR4A1 and breast carcinoma: Cells were admixed with first passage adipose stromal cells (ASC), (10,000 per injection) to maximize tumor cell engraftment as previously described14 and suspended in Matrigel to immobilize the xenograft at the site of injection and provide an optimal environment for tumor cell growth.18 Graded numbers (10–1,000,000 in log10 increments) of the hormone receptor positive breast cancer cell line BT-474, and ASC alone were suspended in Matrigel and injected into separate groups of mice as positive and negative controls, respectively.