Deletion of ERK1 impairs osteoclast formation without any effects on osteoblasts.

<p>WT and ERK1^−/− mouse femur sections were stained with Trichrome Goldner-Masson stain (A) and revealed for TRAP activity (B). Ob.S/BS and Oc.S/BS parameters were calculated from Goldner trichrome and TRAP activity sections, respectively. Data are the means±S.E.M. (n = 5 per group). Data represent the mean±SEM, the Mann-Whitney test was used to calculate the <i>P</i> value.