Protein expression strains

A method for producing a heterologous protein comprising:

• a. providing a fungal host cell having:
• 1) a modified Gsh1 protein which has a reduced level of activity relative to the activity of a wild-type Gsh1 protein of an otherwise identical reference fungal host cell, and/or
• 2) a reduced level of activity of Gsh1 protein relative to the activity of a wild-type Gsh1 protein of an otherwise identical reference fungal host cell, and/or
• 3) a modified GSH1 gene which has a reduced level of activity relative to the activity of a wild-type GSH1 gene of an otherwise identical reference fungal host cell, and/or
• 4) a reduced level of expression of GSH1 gene relative to the level of expression of a wild-type GSH1 gene of an otherwise identical reference fungal host cell, and
• b. culturing the host cell to produce the heterologous protein,
• wherein
• (i) the heterologous protein is a plant or animal protein, and/or
• (ii) the culturing is at a scale of at least 1 liter, and/or
• (iii) the method further comprises purifying the heterologous protein, and/or
• (iv) the method further comprises formulating the heterologous protein with a therapeutically acceptable carrier or diluent thereby to produce a therapeutic product suitable for administration to a human or an animal.