Candida albicans is an opportunistic pathogen that has adapted to live and grow in the human body as its natural environment. Under these conditions, this fungus faces numerous challenges, including oxidative, osmotic and enzymic processes that may damage external and internal structures. In view of the key role of MAP kinase signalling pathways in the physiology of C. albicans, the effect of agents mimicking in vivo environmental conditions on the activation of the p42-44 MAP kinases has been analysed. It has been found that Mkc1p is phosphorylated in the presence of oxidative stress, changes in osmotic pressure, cell wall damage and a decrease in the growth temperature. This phosphorylation is dependent on Pkc1p, indicating that both proteins operate in the same signalling pathway in C. albicans. Under some stimuli, the phosphorylation of Mkc1p required the presence of Hog1p, the MAP kinase of the high osmolarity glycerol (HOG) pathway. This suggests the existence of a new regulatory role, at least under some conditions, for these MAP kinase pathways in yeast.