Table 2.

Top biological functions generated by analyzing the significantly differentially expressed genes by IPA in the A549 cells and rat lungs exposed to crystalline silica.

	A549 cells		Rat lungs
Biological Function	Rank*	Number of molecules**	Rank*	Number of molecules**
Cancer	1	211	1	670
Cellular movement	2	110	2	405
Cellular growth and proliferation	3	180	3	634
Cell death	4	174	9	583
Inflammatory response	5	79	8	361
Cell cycle	6	98	57	254
Cellular development	7	150	13	451
Genetic disorder	8	107	15	164
Antigen presentation	9	27	12	108
Cell-to-cell interaction and communication	10	101	4	369

In general, the biological functions affected by silica exposure, as identified by IPA analysis, in the A549 cells treated with silica at various concentrations (15, 30, 60, 120 and 240 μg/cm²) and exposure durations (60 μg/cm² for 2-, 6-, and 24-hours) were similar. Data obtained from the A549 cells treated with silica at the final concentration of 60 μg/cm² for 24-hours is presented as the representative.

^*Approximately 75 biological function categories were considered for ranking and the ranking was based on the IPA p value of the biological function category.

^**Number of molecules represents the number of differentially expressed genes in the silica exposed A549 cells and rat lungs belonging to the corresponding biological function category.