STX1A and cancer: P-gp (P-glyco-protein, encoded by ABCB1), ABCC5 (ATP binding cassette subfamily C member 5), EZH2 (enhancer of zeste homolog 2), STX1A (syntaxin 1A), and COX-2 (cyclooxygenase-2) serve as MDR enhancers that lead to the poor prognosis of cancer chemotherapeutics, according to our previously published data [19,20,21].