CHL1 and neoplasm: The biological role of CHL1 in BC has been reported in only a single study, in which, in addition to confirming CHL1 downregulation at the mRNA and protein levels in BC tissues and cell lines, the authors found that overexpression of CHL1 impaired cell proliferation and invasion, while CHL1 depletion caused the opposite effect in vitro, and promoted tumour formation in vivo [2].