The common type of myxoid soft tissue sarcomas is myxofibrosarcoma. Clinically, increased tumor grading and staging are frequently observed in myxofibrosarcomas after relentless local recurrences, which may eventually lead to metastatic diseases. However, metastatic myxofibrosarcomas are often refractory to current treatment strategies and constitute the primary cause of sarcoma-related death. Immunohistochemistry staining was applied to analyze myxoid tumors of soft tissue in our previous studies, and p21 protein (Cdc42/Rac)-activated kinase 1 (PAK1) was identified to be significantly upregulated in myxoid soft tissue sarcomas. The PAK1 is a pivotal serine/threonine kinase, which integrates stimuli from various signaling pathways to regulate cell survival, mitosis and cytoskeletal remodeling, etc. We first examined the endogenous PAK1 mRNA and total PAK1 protein levels in various myxoid sarcoma cell lines, including OH931, NMFH1 and NMFH2. This initial screening detected that upregulated PAK1 expression in OH931 and NMFH1, whereas downregulated PAK1 in NMFH2 cells. By wound healing and matrigel transwell assay, we further found that transfection of the expression plasmid carrying wild-type PAK1 gene or PAK1 T423E mutant promoted cell migration and invasion abilities in NMFH2 cells. On the other hand, knockdown of the PAK1 gene by short hairpin RNA interference inhibited the migration rate and invasion ability in NMFH1 cells. By 5-bromo-2-deoxyuridine assay and colony formation assay, we found that either exogenous expression of PAK1 protein or knockdown of PAK1 gene affected cell proliferation and transformation. Interestingly, immunofluorescence demonstrated that treatment with hepatocyte growth factor induced phosphorylation of PAK1 (Thr212) and promoted its nuclear import in NMFH2 cells. In summary, PAK1 plays oncogenic roles in myxoid sarcoma carcinogenesis.