Table 1.

Importance of CD44 ICD in cellular pathways and functions.

Cellular Pathway	Cellular Function	CD44 ICD Interaction(s)	Ref(s)
Cell trafficking	HA endocytosis, pericellular matrix retention, and organization	Absence of ICD	[36]
	CD44–HA endocytosis and degradation	MARCH-VIII ubiquitin ligase	[37]
	CD44 endocytic recycling and stabilization, stemness, and EMT	Hook1, EHD1, and EHD2	[39,40,42]
	Sustained EGFR signaling and survival	Rab7A	[44]
Cytoskeletal organization	Growth, anchorage-independent growth, migration, adhesion, chemotaxis, and leukocyte binding	ERM, merlin, and ankyrin	[4,30,31,52,53,54,55,56,57,60,69,97]
	Migration and proliferation	IQGAP1	[40,67,68]
	Contact inhibition of growth, migration, apoptosis, and proliferation	Merlin	[85,86,87,89,90,91,93]
	Contact inhibition of growth	PAR1b	[98]
Transcription	Apoptosis, survival, migration, and adhesion	iASPP	[40,103]
	CD44 expression	CBP/p300 transcriptional activator	[110]
	Cell cycle progression	CREB	[117]
	Stemness and therapeutic resistance	HIF-2 alpha	[118]
	Stemness and therapeutic resistance	Oct4, Sox2, and Nanog	[119,120]
Metabolism	Survival, stemness, and therapeutic resistance	LDH, PFKFB4, ALDOC, and PDK1	[116,130,132]
	Survival and therapeutic resistance	PKM2	[40,121]