AKT1 and triple-negative breast carcinoma: shRNA-mediated knockdown of AKT1, AKT2 or AKT3 in triple negative breast cancer cells revealed that AKT3 is preferentially required for 3D tumour spheroid growth and in vivo xenograft tumour growth through regulation of the cell-cycle inhibitor p27, whereas knockdown of AKT1 and AKT2 had little effect on tumour growth [67].