CXCL12 and lentivirus infection: Of interest, GFAP+ astrocytes (P = 0.0119) and NG2+ (P = 0.0118) cell numbers were significantly decreased in the CC derived from mice exposed to CPZ for 12 weeks when compared with the CC of mice fed CPZ for 6 weeks (Fig. 6g–l), suggesting that lack of astrocyte targets for lentivirus infection or sufficient OPC numbers to respond to CXCL12 expression prevented remyelination rescue.