An in vitro study on the human melanoma cell line MelIm demonstrates that diclofenac at concentrations from 0.1 to 0.8 mM after 24 h and 48 h of incubation markedly reduces the expression of the transcription factor MYC, monocarboxylate transporter 1 (MCT1), and glucose transporter 1 (GLUT1)—the transmembrane protein responsible for the facilitated diffusion of glucose across a membrane. Here, SLC16A1 is linked to melanoma.