NPR2 and achondroplasia: Furthermore, in vivo studies have shown that: dwarfism occurs in CNP-deficient mice [29], and in mice and patients with Npr2 mutations [33, 34]; mice overexpressing CNP have skeletal overgrowth [35]; targeted overexpression of CNP in chondrocytes can rescue dwarfism in a mouse model of achondroplasia, through a MAPK-dependent pathway [36]; and genome-wide association studies in humans have identified significant associations between the CNP signaling pathway and measures of height and skeletal size [37, 38].