Indeed, in ER/PR-negative Her2-dependent mouse primary tumor cells, the addition of progesterone to charcoal-stripped serum, which is depleted of lipid-soluble hormones such as progesterone, did not affect the ability of Paqr8 overexpression to enhance, or Paqr8 deletion to impair, cell viability following Her2 downregulation. This evidence concerns the gene ESR1 and neoplasm.