Table 1.

Summary of the published studies of gap junction-independent functions of connexins in cell growth and tumorigenicity

References	Cell Systems	Connexin types	GJIC-independent functions in cell/tumor growth	GJIC	Connexin localization
Mesnil et al. [6]	HeLa cells	Cx26, Cx40, Cx43 (transfected)	Cx26—cell growth inhibition; Cx 40 and Cx43—no effect	GJIC for all three connexins	Cx40, Cx43—cell–cell contact; Cx26—cytosol
Huang et al. [12]	Human glioblastoma cells	Cx43 (transfected)	Inhibition on cell and tumor growth	No GJIC	Mainly in the nucleus and cytoplasm
Duflot-Dancer et al. [14]	HeLa cells expressing Cx26	Cx26 mutants: C60F, R87L, R143W (transfected)	P87L and R143W—increased tumorigenicity; C60F—no change	R87L and R143W—no change; C60F—reduced	Cell–cell contact area
Omori and Yamsaki [15]	C6 glioma cells expressing Cx43	Dominant negative Cx43 mutants: L160M and A253V	Both mutants inhibit the effect of wt Cx43 on suppression of tumor growth	A253V—no inhibition on GJIC; L160M—inhibition	No changes of distribution pattern
Krutovskikh et al. [16]	Rat bladder carcinoma BC31 cell	Dominant negative Cx43 mutants: K162A, E166G and T154Y	None of the mutants had effects on cell growth; T154Y accelerated tumor growth.	All three mutants blocked GJIC; T154Y—only transfer of neurobiotin	Wt and T154Y in the lateral membrane; K162A and E166G in the cytoplasm.
Moorby and Patel [17]	3T3 A31 fibroblasts expressing endogenous Cx43 and Neuro2a cells with no endogenous connexins	Cx43 mutants: S255A, S279A, S282A, C-terminal truncated (1–256) and C-terminal domain	In 3T3 cells, S279A and S282A grew slowly; S255A faster than control; mutants affected cell growth without cell contact and GJ; In Neuro2a cells, wt Cx43 and Cx43 C-terminus, but not Cx43(1–256), suppressed cell growth without GJ.	Cells expressing S255A, S279A, and S282A mutants were coupled similarly and prevent PDGF-induced loss of cell coupling in 3T3 cells.	N/A
Olbina and Eckhart [18]	HeLa and C6 glioma cells	Second extracellular mutants of Cx43: F199L, R202E, and E205R	Mutants had similar inhibition of cell growth as wt Cx43	Loss of GJIC by mutants	Wt—plasma membrane; Mutants—membrane and cytoplasm
Dang et al. [19]	Cardiomyocytes and HeLa cells	C-terminal domain of Cx43	Inhibition of cell growth	N/A	Cytoplasm and nucleus
Bond et al. [13]	C6 glioma cells	Cx32 (transfected)	Cell growth in vitro—no change; tumor growth—retarded	No correlation of the function with GJIC	N/A
Qin et al. [20]	MDA-MB-231	Cx43 and Cx26 (retroviral delivery)	Dramatic suppression of tumor growth	No substantial rescue of GJIC	Cytoplasm of cells and xenoplants