SPP1 and sarcoma: Some examples of novel osteoclast‐specific therapeutics already in preclinical development include: bone‐specific targeting of the vacuolar H+ ATPases of the ruffled border,(110) inhibition of the proto‐oncogene tryrosine kinase Src (sarcoma),(111) and small molecule inhibitors of adhesion molecules such as osteopontin.(112) These are in addition to a number of existing agents or targets in development that target osteoblast–osteoclast coupling factors activin A,(113) semaphorins,(114, 115) and sphingosine‐1‐phosphate.(116)