A, representative images of SHEP-21N cells treated with siRNA as indicated. Tetracycline was added (control) or not (N-Myc) to repress or induce N-Myc expression, respectively. siCTL = negative control siRNA; siM6 = siRNA against TRPM6; siM7 = siRNA against TRPM7. B, statistical analysis of cell growth in SHEP-21N cells treated with the indicated siRNA (n = 6; *, p<0.01). Cells were transfected with siRNA, seeded, treated or not treated with Mg2+ or Ca2+ on day 1, and analyzed on day 3 after seeding. C-D, analysis of cell growth in SHEP-21N cells treated for 2 days with the indicated Mg2+ (C) or Ca2+ (D) concentrations (n = 6). E, qRT-PCR analysis of SLC41A1 transcripts in both control and N-Myc-expressing SHEP21N cells (n = 6; n.s., not significant).