Table 3. The production of 1-deoxydihydroceramide after X-ray irradiation.

X-ray dose (Gy)	Irradiation time (h)	N-acyl chain length
		C16	C18	C20	C22	C24	C24:1
3	0	24.66±2.04	6.43±0.25	3.06±0.29	4.29±0.49	2.05±0.31	1.78±0.18
	12	23.15±1.09	6.75±0.84	3.63±0.48	3.52±0.26	2.15±0.25	1.93±0.18
	18	24.01±1.87	7.54±0.36	3.72±0.36	3.69±0.36	2.24±0.21	1.69±0.24
	24	27.99±1.94	10.35±0.75***	3.04±0.33	4.59±0.47	3.63±0.37***	1.72±0.33
6	0	23.58±1.83	6.88±0.42	3.15±0.34	3.00±0.16	3.09±0.24	1.59±0.36
	12	26.35±2.52	7.42±0.45	2.86±0.21	3.20±0.21	3.96±0.45	1.69±0.25
	18	28.50±2.84	9.42±1.21	3.49±0.51	3.61±0.33	4.08±0.41	1.27±0.11
	24	30.93±3.21**	11.61±1.25***	3.44±0.41	5.47±0.46***	5.20±0.58**	2.80±0.14

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