CTRP3 has been linked to normal and pathogenic cellular proliferation, growth and development. CTRP3 has been consistently shown to stimulate the proliferation of chondrogenic precursors, chondrocytes, and osteocytes, in vitro, through activation of ERK1/2 and PI3K pathways (1, 3, 27, 44, 82). During early development CTRP3 is detected in developing chondrocytes (43) and cartilage (44) which has led to the hypothesis that CTRP3 Is essential for normal cartilage and bone development. In support of this CTRP3 is appears to be essential for proper mandible formation through perichondrium maintenance and new cartilage formation (82). However, the role of CTRP in development may be dispensatory as CTRP3-knockout animals do not demonstrate a growth phenotype indicating a possible compensatory mechanism during development. However, CTRP3-knockout mice do exhibit increased susceptibility to collagen-induced arthritis, indicating CTRP3 may be important for the maintenance and repair of cartilage tissue (46). However, elevated CTRP3 may also be detrimental as CTRP3 is highly secreted from and increases growth rates of osteosarcoma and chondroblastoma tumor cell lines indicating that CTRP3 may be linked to these types of cancers (54).However, no
