Table 1.

Factors associated with T_RM development and maintenance. Factors are listed by their order of appearance in the text

Factor	Expression	Function	References
CD103	Expressed mainly on CD8+ TRM in certain tissues (e.g., gut)	Interacts with E-cadherin, tethering CD8+ TRM to epithelial cells	[1, 16, 17]
CD69	Expressed on most, but not all TRM	Associates with and inhibits S1PR1, blocking tissue egress	[1, 16, 17]
KLF2	Downregulated in TRM	Transcription factor required for S1PR1 expression	[1, 18••]
S1PR1	Downregulated in TRM	Mediates tissue egress in response to its ligand, S1P	[1, 19]
T-bet	Downregulated in TRM	Transcription factor that suppresses TRM differentiation	[18••, 20]
Eomesodermin	Downregulated in TRM	Transcription factor that suppresses TRM differentiation	[18••, 20]
Hobit	Upregulated in mouse but apparently not human TRM	Suppresses KLF2, central regulator of mouse TRM	[18••, 21]
Blimp-1	Collaborates with Hobit in mouse TRM	Central regulator of mouse TRM	[18••, 21]
mTOR kinase	Expression may be required for accumulation of mouse TRM	Regulator of cell differentiation and survival	[22, 23]
FABP4, FABP5	Required for long-term survival of TRM in mouse skin	Fatty acid binding proteins, promote lipid uptake and transport	[24•]
Runx3	Promotes mouse TRM differentiation and maintenance	Transcription factor that regulates tissue-residency in multiple cell types	[15, 25•]
P2RX7	Supports long-lived TRM	Sensor for extracellular ATP; detects injury and inflammation	[26•]
Bhlhe40	Required for development and polyfunctionality of CD8+ TRM and TIL	Transcription factor; programs mitochondrial metabolism and active chromatin state	[27•]

CD cluster of differentiation, KLF2 Krüppel-like Factor 2, S1PR1 sphingosine-1-phosphate receptor 1, T-bet T-box transcription factor expressed in T cells, Hobit Homolog of Blimp-1 in T cells, Blimp-1 B lymphocyte maturation promoting transcription factor-1, mTOR mammalian target of rapamycin, FABP fatty acid binding protein, Runx3 Runt-related transcription factor 3, P2RX7 purinergic receptor P2X7, Bhlhe40 Basic helix-loop-helix family member E40