LEP and Obesity: In addition, factors secreted from adipose tissue that are elevated in obesity, such as leptin, visfatin, or those contained in EVs, have been shown to promote processes associated with tumor development, such as angiogenesis, invasion, viability, metalloproteinase activation, and ROS production, and do so by elevating ERK and PI3K/Akt signaling among other mechanisms [24,25,26].