For instance, Rutkowski et al. [25] assessed clinical response to imatinib mesylate among 31 patients with locally advanced, inoperable, or metastatic DFSP with cytogenetically proven presence of the COL1a1-PDGFRβ fusion protein, as its mechanism of action involves the inhibition of autophosphorylation and activation of multiple proteins by tyrosine kinases [26]. Here, COL1A1 is linked to dermatofibrosarcoma protuberans.