Table 2.

Genes associated with late phase formalin licking.

Gene	Protein	Correlation	Pain/Analgesia Models	References†
Pla2g4e	Phospholipase A2 (PLA2)	-0.96	Formalin Nerve injury Carrageenan	[27,28,39,40] [40] [28,40]
Mapk8	c-Jun N-terminal kinase 1 (MAPK8, JNK1)	-0.91	Nerve Injury	[20]
RIKEN 4833416E15	(Unknown)	0.90	-
Scn2b	Sodium channel beta2 subunit	0.89	Formalin	[30]
Kcnj9	G-protein-gated inwardly rectifying K+ channel subunit 3 (Kir3.3, GIRK3)	-0.89	Morphine	[41]

The results of correlation analysis between strain-specific late phase formalin scores and a spinal cord gene expression database. The top 5 most-strongly-linked genes and the proteins they encode, along with the correlation coefficients and the direction of correlation is provided. Positive correlation signifies greater gene expression corresponding to greater levels of pain behavior.

^†References for pain-related investigations specific to the named gene or closely related gene family members.