PLAU and severe combined immunodeficiency: By using an optimized hepatocyte differentiation protocol on transgenic mice, which carry the uPA (urokinase-type plasminogen activator) gene driven by the major urinary protein promoter onto a SCID (severe combined immunodeficiency)/beige background, HLCs differentiated from both hESCs and patient-specific iPSCs were able to engraft and undergo further maturation in vivo.