MCL1 and melanoma: The object of this study is a comparison of the influence of mTOR inhibitor everolimus in the concentration range between 20 nM and 10 μM, used individually and in combination with selected downstream protein kinases inhibitors: LY294002 (PI3K), U0126 (ERK1/2), AS-703026 (MEK) and MK-2206 (AKT) on the expression of pro-survival proteins: p-Bcl-2 (S70), p-Bcl-2 (T56), Bcl-2, Bcl-xL, Mcl-1, activity of caspase-3, proliferation and induction of apoptosis in melanoma cells.