Table 2.

Cell-specific normal and impaired functions of IGF-1 signaling in the colonic epithelial cells.

Cell Type	Paracrine/Autocrine IGF-1 Signaling
	Normal Function	Effects of Functional Impairments
Absorptive cell (colonocyte)	cell proliferation ↑ cell regeneration ↑ cell apoptosis ↓ protein catabolism and energy consumption ↓ expansion of ISCs and secretory cells mucosal barrier immunity ↔ intestinal immune homeostasis ↔	dysbiosis ↑ translocation of bacteria ↑ cell regeneration in colitis ↑ mucosal barrier restoration in colitis ↑ loss of intestinal homeostasis
Goblet cell	cell regeneration ↑ proliferation ↑	loss of intestinal homeostasis
Intestinal (colonic) stem cell	cell regeneration ↑ cell expansion SC stemness ○ SC renewal ○ pluripotency ○ differentiation	loss of intestinal homeostasis
Paneth-like cell	epithelial cell protection and repair ↑ mucosal inflammatory responses ↓ intestinal tropic effect of GLP-2 ↑	unknown

Legend: ↑/↓: increase/decrease; stimulation/inhibition; ↔: maintenance; GLP-2: glucagon-like peptide 2; IGF: insulin-like growth factor; (I)SCs: (intestinal) stem cells.