PGR and breast cancer: Importantly, PKN1 expression has been shown to be elevated intriple-negative breast cancer samples (i.e., when ER, PgR, and the avianerythroblastic leukemia viral oncogene homolog 2 (ERBB2, also known as Her2/neu) aredownregulated or absent), that usually show a very aggressive phenotype.11 Therefore, we may conclude that the increase in PKN1expression we observed is associated with more aggressive tumor phenotypes.