Therefore, the possible outcomes of the treatment with TKI sunitinib are: (i) direct inhibition of the proliferation of stromal cells as we detected in cell lines under in vitro conditions; (ii) differentiation of stromal cells to fibroblast-like cells as we detected in tumor tissue samples; (iii) indirect inhibition of RANKL/RANK signaling in giant cells as described by O’Sullivan and colleagues [48]. The gene discussed is TNFSF11; the disease is neoplasm.