let-7 is upregulated in miR-26a-overexpressing tumors. (a) Relative expression of indicated miRNAs in miR-26a-overexpressing A375 tumors and control tumors (n=5 tumors/group). (b) Fold changes in the expression of indicated miRNAs of miR-26a-overexpressing versus control melanoma cell lines. (c, d) Relative expression of indicated miRNAs in miR-26a-overexpressing DU145 (c) and SK-HEP-1 (d) and control tumors. (e) Correlation of miR-26a and let-7 expression within normal human tissues, as determined by linear regression. (f, g) Indicated cells were transfected with miR-26a precursor (pre-26a), miR-26a precursor plus let-7 family inhibitor (pre-26+let-7 FI) or negative controls (N.C.). Forty-eight hours post transfection, let-7 expression (determined using QRT–PCR) (f) and cell proliferation (determined using MTS analysis) (g) were measured. (h) Relative expression of indicated pri-miRNAs in miR-26a-overexpressing and control tumors. Data are shown as means±s.e.m. Statistical significance, determined using two-tailed Student’s t-test (a, c, d, f–h), is indicated by *P<0.05; **P<0.01; and ***P<0.005.