MAPK8 and systemic sclerosis: An additional outcome of Ha-Ras overexpression in mDF cells included the rapid activation of ERK1/2 signalling (Figure 2A), which is part of the self-propagating loop of ROS production, Ha-Ras stabilization and collagen I accumulation in SSc [15,16] and also of JNK and p38 MAPK (data not shown).