MAP2K5 and osteoporosis: It is of interest that while Erk5 has not been implicated in genome-wide association studies (GWAS) in the osteoporosis field to date36, a network-based meta analysis of gene expression profiles in women with bone mineral variations identified Mekk3 (Mek kinase 3), which encodes an upstream kinase of MEK5 in the ERK5 pathway, as one of five candidate genes to be associated with bone mineral density37.