STAT3 and cancer: Furthermore, leptin initiates cancer progression by affecting the initiation of signal transducers and activator of transcription 3 (STAT-3) and STAT-3 terminal gene expression resulting in melanocortin inhibition, stimulation of signal transducers and activator of transcription 5 (STAT-5), leading to altered gene expression, and stimulation of PI3K (Phosphatidylinositol-3-kinase), which interacts with insulin receptor pathways [88,92,93,94].