Provided herein are methods of treating diseases associated with vascular calcification and/or cardiovascular disease in a subject by using the level of a biomarker, in particular, snail homolog 1 (Snai1), phosphosmad2, phosphosmad3, urinary protein, dickkopf homolog 1 (Dkk1), collagen type 1 alpha 1 (Col1a1), activin (e.g., free activin), runt-related transcription factor 2 (Runx2), alkaline phosphatase (Alp), bone-specific alkaline phosphatase (BSAP), C-terminal type 1 collagen telopeptide (CTX), osterix, Klotho, alpha-smooth muscle actin (alpha-SMA), myocardin (MYOCD), activin receptor type 2A (ActRIIA), axis inhibition protein 2 (Axin2), and/or smooth muscle protein 22-alpha (Sm22-alpha), as an indicator(s) of responsiveness of the subject to the treatment, efficacy of the treatment, or appropriate dosage for the treatment with an activin type II receptor signaling inhibitor. Provided herein are methods of bone resorption in a subject by using the level of a biomarker, in particular, snail homolog 1 (Snai1), phosphosmad2, phosphosmad3, urinary protein, dickkopf homolog 1 (Dkk1), collagen type 1 alpha 1 (Col1a1), activin (e.g., free activin), runt-related transcription factor 2 (Runx2), alkaline phosphatase (Alp), bone-specific alkaline phosphatase (BSAP), c-terminal telopeptide (CTX), osterix, Klotho, alpha-smooth muscle actin (alpha-SMA), myocardin (MYOCD), activin receptor type 2A (ActRIIA), axis inhibition protein 2 (Axin2), and/or smooth muscle protein 22-alpha (Sm22-alpha), as an indicator(s) of responsiveness of the subject to the treatment, efficacy of the treatment, or appropriate dosage for the treatment with an activin type II receptor signaling inhibitor.
