Table 2.

mRNA and protein expression of balloon cells (BC) and giant cells (GC) of mTOR and cell growth markers.

Category	Cell marker	BC	GC	Function	Notes and references
	pAkt	++	+	TSC 1 and 2 suppressor	mRNA data suggest normal expression in GC but increased in BC (Rossini et al., 2017; Schick et al., 2007a)
mTOR pathway Cell growth marker	Hamartin	u	-	Tumor suppressor; mTOR suppressor	BC/GC (Jozwiak et al., 2004; Grajkowska et al., 2008)
	Tuberin	u	-
	pPDK	++	++	Signal transduction in mTOR	mRNA expression is also shown in BC/GC (Rossini et al., 2017; Schick et al., 2007a)
	p4EBP1	+	+	Translation initiation factor	mRNA expression is also shown in BC/GC; More focal, more variable expression in BC (Yasin et al., 2010)
	pTuberin	++	++	Inactivated tuberin/TSC2	Only shown in mRNA so far (Schick et al., 2007a)
	Actin Stress Fiber	++	++	Disrupts actin skeleton	Only shown in mRNA so far (Schick et al., 2007a)
	pS6	++	++	Protein synthesis, cell proliferation, apoptosis, and metabolism	BC/GC (Rossini et al., 2017)
	p-p70(S6k)	++	++	Cell proliferation, growth, and cell cycle progression	Only shown in mRNA so far (Schick et al., 2007a)
Cell growth pathways	MCM2	+	+	G1 cell stage marker	unable to be activated with stem cell mitogens in BC/GC (Yasin et al., 2010)
	IGF2	++	+	Insulin growth factor	Only shown in mRNA so far; Normal expression in GC (Baybis et al., 2004)
	Ki67	-	+	Cell proliferation marker and immature neuronal marker	BC (Munakata et al., 2013) GC (Crino et al., 1996; Crino et al., 1997)
Inflammation markers	LILRB2	+	+++	Modulates neurite growth, synaptic plasticity, and inflammatory responses	BC/GC (Yue et al., 2019)
	TLR4	++	++	Toll-like receptor involved in neurogenesis	BC/GC (Arena et al., 2019)
	IL-1β	++	++	Proinflammatory cytokine involved in neuronal development	BC/GC (Arena et al., 2019)
	IL-6/IL-6R	+++	+++	Proinflammatory cytokine involved in neuronal development	Colocalization with GFAP in BC, but not GC (Shu et al., 2010)
	IL-17/IL17R	+	+	Activates innate and adaptive immunity	2x higher compared to cortex in BC/GC (He et al., 2013)
	TGF-β	u	u	Regulates response to cell injury, including modulating cell growth	Only shown in mRNA so far (Baybis et al., 2004)
	FPR2	+	+	Inflammatory resolution in CNS; Negatively correlated with NF-kB	Weakly shown in GC/BC (Huang et al., 2022)

-: “not expressed” u: “Under expressed”; +: Expressed (may be weakly expressed or normal expression); ++: “Overexpressed”; +++: “Strongly Expressed.”All studies examined human cortical samples. Unless otherwise noted, all studies are immunohistochemical studies of protein expression.