Compounds of formula I: in free or salt or solvate form, where R1, R2, R3 and R20 have the meanings as indicated in the specification, are useful for treating diseases mediated by the ALK-5 and/or ALK-4 receptor. Pharmaceutical compositions that contain the compounds and processes for preparing the compounds are also described. These compounds are useful for the treatment of inflammatory or obstructive airways diseases such as pulmonary hypertension, pulmonary fibrosis, liver fibrosis, cancer, muscle diseases such as muscle atrophies and muscle dystrophies, and systemic skeletal disorders such as osteoporosis.