Table 2. Summary of newly identified homeobox regulators of neuronal differentiation.

Neuron class	type	location	lineage history	Previously identified identity regulator for this neuron class	Newly described homeobox gene required for identity (this paper)
no identity regulator known before
AVJ	peptidergic interneuron	lateral ganglion	ABalap(a/p)pppa	none	lin-11/LHX1
					unc-30/PITX
					mls-2/HMX
ADA	glutamatergic interneuron	anterior deirid lineage	ABp(l/r)apaaaapp	none	ceh-14/LHX3
					unc-86/BRN3
					unc-62/MEIS
RMG	peptidergic interneuron	anterior deirid lineage	ABp(l/r)apaaapp	none	unc-86/BRN3
					ceh-13/HOX
RIC	octopaminergic interneuron	lateral ganglion	ABp(l/r)ppaaaapp	none	unc-62/MEIS
RIR	cholinergic interneuron	ventral ganglion	ABprpapppaa	none	unc-86/POU
RIP	peptidergic interneuron	anterior ganglion	AB alpapaaaa, AB arappaaaa	none	ttx-1/OTX
RIB	GABAergic interneuron	lateral ganglion	AB p(l/r)paappap	none	ttx-1/OTX
AIN	cholinergic interneuron	lateral ganglion	ABalaaaalal ABalaapaaar	none	tab-1/BSX
OLQ	glutamatergic sensory	anterior ganglion	ABalap(a/p)papaa ABp(l/r)paaappaa	none	vab-3/PAX6
IL1	glutamatergic sensory	anterior ganglion	ABalapappaaa ABalappppaaa ABalapaappaa ABalaappppaa ABalppapppaa ABarapppppaa	none 1	ceh-32/SIX3/6
PVW	peptidergic interneuron	lumbar ganglion	T(L/R).ppa	none	ceh-14/LHX3
LUA	glutamatergic interneuron	lumbar ganglion	ABp(l/r)pppaapap	none	egl-5/HOX
only non-homeobox regulator known before
AWA	peptidergic sensory	lateral ganglion	ABp(l/r)aapapaa	odr-7 (nuclear receptor)	egl-5/HOX
RME	GABAergic motor neuron	nerve ring	ABalapppaap ABalaaaar(l/r)p ABplpappaaa	nhr-67/TLX (nuclear receptor)	ceh-32/SIX3
PDA	cholinergic motor neuron		ABprpppaaaa	unc-3/COE (Zn finger)	egl-5/HOX
complements incomplete combination of previously described homeobox genes
AIA	cholinergic interneuron	ventral ganglion	ABp(l/r)ppaappa	ttx-3/LHX2	unc-39/SIX4
AIM	glutamatergic interneuron	ventral ganglion	ABp(l/r)paapppa	unc-86/BRN3	mls-2/HMX ceh-14/LHX3
AIZ	glutamatergic interneuron	anterior deirid lineage	AB p(l/r)apaaapav	unc-86/BRN3	ceh-43/DLX
AQR	glutamatergic sensory neuron	head	QR.ap	unc-86/BRN3 lin-39/HOX egl-13/SoxD	unc-62/MEIS ceh-20/PBX
FLP	glutamatergic sensory neuron	anterior deirid lineage	ABp(l/r)apaaapad	unc-86/BRN3 mec-3/LHX	unc-62/MEIS ceh-20/PBX
AVD	glutamatergic interneuron	lateral ganglion	ABalaaapalr ABalaaapprl	unc-42/PROP1 unc-3/COE cfi-1/ARID	tab-1/BSX
OLL	glutamatergic sensory	anterior ganglion	ABalppppapaa ABpraaapapaa	vab-3/PAX6	ceh-32/SIX3
URY	glutamatergic sensory	anterior ganglion	ABalap(a/p)papp ABp(l/r)paaappp	vab-3/PAX6	ceh-32/SIX3
URB	cholinergic interneuron	anterior ganglion	AB plaapaapa AB praapaapa	unc-86/BRN3	vab-3/PAX6
URA	cholinergic interneuron	anterior ganglion	AB plaaaaaaa, AB arpapaaaa, AB plpaaapaa, AB prpaaapaa	unc-86/BRN3	vab-3/PAX6

¹ we had previously assumed vab-3 to be a candidate terminal selector for the IL1 neurons [48]; however, more recent expression pattern analysis indicates that vab-3 is not continuously expressed in IL1 [6]. Hence, the reported IL1 differentiation defects of vab-3 mutants are likely a reflection of earlier function of vab-3 in the lineage.