As such, we characterise the PP1β holoenzyme MLCP as a novel dynamic regulator of the AR, and demonstrate that through downregulation of the endogenous MLCP regulatory inhibitory subunit, PPP1R14C [28], ligand induced AR nuclear translocation, stability, and ultimately AR transcriptional activity is significantly reduced in distinct PC cell line models representing both androgen sensitivity and castration resistance. Here, AR is linked to pachyonychia congenita.