Table 1.

MC1R genotype, eumelanin and pheomelanin content, and response to α-MSH in various assays of HM strains

Strain	MC1R genotype	Eumelanin (ng/106 cells)	Pheomelanin (ng/106 cells)	cAMP	Tyrosinase activity	Apoptosis	H2O2	CPD
R/R
1n	R160W/R160W	656	430	−	−	−	+	−
2n	R160W/D294H	2304	1486	−	−	−	−	−
3a	R160W/D294H	4080	2900	−	−	−	−	−
4n	R151C/D294H	14,896	4090	−	−	−	−	−
5n	R151C/R160W	910	1420	−	−	−	−	−
R/r
6n	R160W/V60L	7712	7880	ND	−	−	ND	−
7a	R160W/V60L	4990	4080	−	−	−	−	−
R/p
8n	R160W/R163Q	6990	2230	±	+	+	+	+
9a	R151C/V92M	2380	3230	±	+	+	+	+
R/+
10n	R160W/+	3430	5550	±	−	−	+	+
11n	D294H/+	33,840	19,610	±	±	+	+	+
12a	R151C/+	5120	2394	+	+	+	+	+
r/+
13n	V60L/+	4380	6200	+	+	+	+	+
p/+
14n	V92M/+	2608	3168	+	+	*	+	+
15a	V92M/+	4288	6489	+	+	+	+	+
16n	R163Q/+	1248	870	+	+	+	+	+
+/+
17n	+/+	1232	715	+	+	ND	+	+
18n	+/+	32,880	13,608	ND	+	+	+	ND
19n	+/+	400	140	+	+	+	+	+
20a	+/+	6256	15,732	+	+	+	+	+
21a	+/+	13,088	10,683	+	+	+	+	+

Strains: R, RHC alleles; r, V/60L; p, pseudoallele; +, wild-type allele; a, adult; n, neonatal. Response to α-MSH in the various assays: +, high response; −, lack of response; ±, partial response; ND, not determined.

^*most resistant strain to UV-induced apoptosis even 48 h after UV exposure.