HSL triacylglycerol glycerol fatty acids PKG1 PKG1 cGMP PKA cat PKA reg cAMP PKA cat PKA reg PKA cat PKA reg HSL LABEL Perilipin 1 HSL Perilipin 1 LABEL Perilipin 1 HSL 2 4 P@S855 P@S950 P@S951 cGMP N:2 N:2 N:2 N:2 cAMP cAMP cAMP N:2 cAMP @S950 @S951 @S855 P @S951 @S950 @S855 @S951 @S950 @S855