CXCL12 and asthma: Four genes (i.e. CCL2, CCL13, CXCL12, IL8) that (1) were members of the GO:0008009~chemokine activity ontological category, which was significantly over-represented among genes differentially expressed in response to vitamin D treatment in both fatal asthma- and non-asthma-derived ASM [S5 and S6 Tables], and (2) were differentially expressed in fatal asthma vs. non-asthma-derived ASM at baseline [S2 Table] were selected for detailed examination [Fig 1; Table 5].