In osteoclasts cultured in vitro, exogenous teleost CT protects from chemically induced apoptosis26,27 through the inhibition of caspase activation27 via cAMP26 and pERK pathways.27 Generally, phosphorylation of ERK1/2 promotes cell survival; however, activation can also be proapoptotic.28 In prostate cancer cell lines, exogenous CT also protects from chemically induced apoptosis29,30 again via inhibition of caspase activation.30 In these cells, knockdown of CTR induces apoptosis,31 suggesting autocrine activation of CTR. Here, CALCR is linked to prostate cancer.