TAP1 and melanoma: In contrast, overexpression of miR-21-3p did not affect TAP1 mRNA levels (Figure 4d) in the melanoma cell lines analyzed, but interfered with TAP1 protein levels (Figure 4g,i) with a 25% decreased expression in melanoma transfectants compared to controls, potentially indicating a different type of action of miR-21-3p or miR-26-5p.