Table 2. The production of 1-deoxyceramide after X-ray irradiation.

X-ray dose (Gy)	Irradiation time (h)	N-acyl chain length
		C16	C18	C20	C22	C24	C24:1
3	0	12.80±1.03	3.95±0.24	3.62±0.34	2.80±0.22	13.76±1.05	12.28±1.13
	12	14.41±1.41	4.85±0.75	3.71±0.25	5.46±0.58	13.33±0.94	12.69±1.56
	18	15.50±1.21**	4.96±0.34	3.71±0.34	6.49±0.45	16.30±1.21	15.68±1.09***
	24	17.11±1.07***	6.05±0.75**	6.57±0.69***	6.28±0.69***	27.98±1.53***	17.07±0.46***
6	0	13.26±1.24	3.08±0.33	2.65±0.53	2.86±0.25	11.58±1.03	11.75±1.04
	12	15.80±1.08	5.34±0.42	3.57±0.43	5.20±0.13	16.12±1.29**	13.20±0.25
	18	20.80±1.98***	6.63±0.78***	5.06±0.65	6.41±0.87***	22.42±1.22***	16.34±1.98*
	24	22.52±3.87***	7.51±0.54***	8.17±1.09***	8.58±0.48***	32.14±2.52***	23.9±3.25***

Values are presented as mean±standard deviation (pmol/mg). ^*p<0.05, ^**p<0.01, and ^***p<0.001 compared to untreated normal human epidermal keratinocytes.