Calu is an Etruscan chthonic deity, often equated with the Etruscan equivalent to the Greek Hades, Aita. He is identified by his wolf attributes, such as a wolf-like appearance or a human with a wolf-skin cap. The visual representations of the cult of Calu seem to contain common elements with the Roman cult of Lupercalia and the Faliscan cult of the Hirpi Sorani ("wolves of Soranus", from Sabine hirpus "wolf").
Calumenin (CALU) is a calcium-binding protein localized in the endoplasmic reticulum (ER) and is involved in such ER functions as protein folding and sorting. Calumenin is a member of the EF-hand superfamily in the ER and Golgi apparatus named CERC. CERC is an acronym for its family members Cab-45, reticulocalbin, Erc-55 ( RCN2), and calumenin. The CALU gene encodes a deduced 315-amino acid protein containing 6 EF-hand motifs, 1 potential N-glycosylation site, and a C-terminal ER retention signal. The human and mouse CALU proteins are 98% identical. CALU mRNA is ubiquitously expressed in human tissues and maps to 7q32.