Table 1. Changes in myometrial tissue expression of cAMP signalling components associated with human pregnancy and term gestation labour.

Component of cAMP signalling	Pregnancya		Labourb
	mRNA	protein	mRNA	protein
Gαs	[-] [26]	[-] [25]; ⇑ [25,143]	[-] [30]	[-] [30]; ⇓ [25]
Adenylate cyclases (ACs)	n/a	⇓ AC1, AC3, AC8, AC9 [144]; ⇑ AC2, AC4, AC5, AC7 [144]	n/a	n/a
A-kinase anchoring proteins (AKAPs)	n/a	[-] AKAP95, [-] AKAP79 [24]	↓ AKAP79 [30]	[-] AKAP79 [30]; [-] AKAP95, [-] AKAP79 [24]; ↓ AKAP79 [87]
Protein kinase A (PKA) – regulatory (R) subunits	↑ RIIα [24]	[-] RIα, ↑ RIIα [24]; ↑ RIIα [24]	↓ RIIα [24,30]	[-] RIα [24], ↓ RIIα [24,30]; ↓ RIIα/β [24,87]
Protein kinase A (PKA) – catalytic (C) subunits	n/a	[-] Cα, [-] Cβ [24]; ↑ Cα/β [24]	n/a	[-] Cα, [-] Cβ [24]; ↓ Cα/β [24,87]
Exchange protein directly activated by cAMP 1 (EPAC1)	n/a	n/a	↑ [30]	↑ [30]
cAMP-phosphodiesterases (PDEs)	[-] PDE4A, PDE4C, PDE4D [145]; ↑ PDE4B2 [145]	⇑ PDE4B, [=] PDE4D [27]	[-] PDE4B [30]	↓ PDE4B [30]

Associated references in brackets, where qualitative (⇓/⇑/[=]) or quantitative (↑/↓/[-]) findings presented were based on comparisons between ^apregnant (term gestation) vs non-pregnant and ^bterm labouring vs term non-labouring women (decrease (⇓↓)/increase (⇑↑)/no change ([=][-]) of former compared with latter for each pair of comparisons) for myometrial tissues obtained from the lower uterine segment at Caesarean section; n/a indicates the comparison has not been assessed; changes at protein level that were specifically observed in membrane fractions are shown in bold font.