As there are no studies so far investigating the role of miRNA449a in pNETs and as there is evidence of other miRNAs not distinctly having either a tumor suppressive- or oncogenic function, the results of this study indicate, that miRNA449a does function as an oncogene in pNETs in an interplay with HDAC3 and HDAC4. Here, HDAC4 is linked to neoplasm.