TNFSF11 and Osteopenia: Our data also exclude tissue hypersensitivity (pseudohyperparathyroidism) to PTH postulated as pathogenetic mechanism for the osteopenia (David-Vizcarra et al, 2010; Parisien et al, 1990), since the secretion of Rankl in osteoblasts from MLII mice was not affected in response to PTH stimulation.