PAK4 and cancer: Li et al. [8] found that PSC-derived exosomal miR-5703 could target CKLF-like MARVEL transmembrane domain 4 (CMTM4) to inhibit its expression in PDAC cells, thus upregulating p21-activated kinase 4 (PAK4) expression and activating the PI3K/Akt pathway, promoting cancer cell proliferation.